Send Message 1.0.0: one PIN, one place to send from; Slack 1.3.0 and ProdCom 1.4.0 become messaging providers

A new send-message module owns everything a dashboard sends: the PIN
(switchable off in admin), the unlock tokens, the Send message and Quick
replies tiles, the quick replies and quick emojis. It opens no upstream
connection of its own — it finds every module declaring
provides: ["messaging"] through the shell's module list and hands each
message to that module's POST /messaging/send over loopback, so Slack keeps
its one Slack connection and ProdCom its one ProdCom connection. Providers
check the browser's unlock token with GET /verify over loopback before
touching their upstream, so no browser on the network can post as the
location without having entered the PIN here.

Slack 1.3.0 is view-only plus reactions: the Sending group, PIN, send tiles
and quick replies are gone; it serves the messaging descriptor (channels as
recipients) and its reactions ride on the Send Message unlock. A layout's
old Send message / Quick replies tiles draw nothing until removed.

ProdCom 1.4.0 serves the descriptor as identities — only channels with
typingEnabled, since typed text goes out *as* a channel — and posts with
POST /api/v1/channels/{id}/send. Its tile is a click-to-target like Slack's
(accent stripe along the bottom), and typed entries carry a keyboard mark.

The tiles: click any Slack or ProdCom transcript to point sends there; a
Send as menu (only for platforms with identities, hidden otherwise) picks
the ProdCom channel to speak as; the choice is saved with the tile so named
layouts remember it. Wording follows the role — "Send message to #ops…" /
"Send message to ProdCom as FOH…". The PIN pad's dots ride on a real
numeric input so a phone's keyboard appears. Outcome is an icon beside
Send (check / blocked, five seconds, sentence as tooltip). A pill on the
box's bottom edge trades box height for rows of quick-emoji keys, a row
at a time; the single row scrolls sideways on a narrow tile with Send
pinned in place.

The module guide documents the provider contract and the page bus
(window.proddashMessaging + proddash:messaging:* events) the tiles share;
the ProdCom mock gained the send route.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

README.md

@@ -318,7 +318,13 @@ below. Nothing is installed without someone clicking.
 - **ProdCom** — live transcript stream with in-place updates of in-progress
   speech, channel colors, per-tile channel visibility toggles and group
   presets, timestamps, text size, a top-down / bottom-up direction toggle
-  and jump-to-latest in the title bar.
+  and jump-to-latest in the title bar. Text typed into a channel (from a
+  dashboard, or ProdCom's own box) is marked with a keyboard; an automation's
+  with a bolt. The module also offers its channels to **Send Message** as
+  identities: a click anywhere in the transcript points that module's tiles
+  at ProdCom (the tile's bottom edge lights up in the accent color), and the
+  channel the text goes out *as* is picked from their Send as menu — only
+  channels ProdCom lets text be typed onto are offered.
   Admin config: ProdCom server (host : port), API key.
   Tile settings: channel icons, direction and timestamps.
 - **ProPresenter** — what's live and what's next, with slide progress,
@@ -406,29 +412,47 @@ below. Nothing is installed without someone clicking.
   has signed up for are hidden until you ask for them — that list comes from
   the service type, since Planning Center only returns a team once somebody
   is on it.
-- **Slack** — live transcripts of this location's Slack channels, plus
-  PIN-protected sending as the location. The ＋ picker lists one transcript
-  tile per configured channel, titled `#channel`, and two send surfaces (one
-  of each per dashboard): **Send message**, a free-text box with the admin's
-  quick emojis one press away, and **Quick replies**, a grid of preset
-  buttons. Both post to the channel of whichever transcript was clicked last
-  — its bottom edge lights up in the accent color — and to the first
-  configured channel until one is clicked. Messages arrive with avatars,
-  names and times, Slack's inline formatting and the workspace's custom
-  emoji; a right-click on one opens the reaction menu, and text size and
-  jump-to-latest sit in the title bar. Nothing leaves the machine until the
-  PIN is entered: one PIN unlocks every Slack tile on that dashboard page
-  until the auto-lock idles out, a reload asks again, and the lock button on
-  a send tile's title bar ends it early.
-  Admin config is in four groups: **Slack account** (the location account's
+- **Slack** — live transcripts of this location's Slack channels. The ＋
+  picker lists one transcript tile per configured channel, titled
+  `#channel`. Messages arrive with avatars, names and times, Slack's inline
+  formatting and the workspace's custom emoji; text size and jump-to-latest
+  sit in the title bar. Sending is the **Send Message** module's: a click
+  anywhere in a transcript points its tiles at that channel (the bottom
+  edge lights up in the accent color), and a message then leaves through
+  this module's one Slack connection, as the location. A right-click on a
+  message opens the reaction menu, which rides on the same unlock — with
+  the page locked, or no Send message tile on it, it says so instead of
+  reacting. This module has no PIN, send tile or quick replies of its own.
+  Admin config is in three groups: **Slack account** (the location account's
   User OAuth Token — `xoxp-…`, so messages are literally from the campus —
   or a bot token plus "Send as"), **Channels** (the joined channels to
-  follow, one transcript tile each), **Transcript** (refresh interval,
-  messages kept, thread replies) and **Sending** (the switch on the group's
-  title row, a 4–8 digit PIN, auto-lock minutes, quick replies one per line
-  as `Label | Message` — add `| #channel` to bind one to a channel — and up
-  to eight quick emojis).
+  follow, one transcript tile and one Send Message destination each) and
+  **Transcript** (refresh interval, messages kept, thread replies).
   Tile settings: avatars, timestamps, names and channel notices.
+- **Send Message** — the one place a dashboard sends from, whatever the
+  platform. Two tiles, one of each per dashboard: **Send message**, a
+  free-text box with the admin's quick emojis one press away, and **Quick
+  replies**, a grid of preset buttons. Both go wherever the operator last
+  pointed them with a click on a Slack or ProdCom transcript. A platform
+  whose destinations are identities rather than recipients — ProdCom, where
+  typed text goes out *as* a channel — also gets a **Send as** menu in the
+  title bar listing those identities; the menu exists only while such a
+  platform is installed, and Slack's channels are never in it. The choice is
+  saved with the tile, so a named layout remembers it; the transcript it
+  points at carries the accent stripe. The module
+  owns no connection of its own — it finds every installed module that
+  offers messaging and hands the message to it over loopback — and it owns
+  the PIN: nothing leaves the machine until it is entered on one of its
+  tiles, one entry unlocks every messaging tile on that dashboard page
+  (Slack's reaction menu included) until the auto-lock idles out, a reload
+  asks again, and the lock button ends it early. The PIN pad takes taps, a
+  keyboard, or a phone's — tapping the dots raises it. The PIN can be
+  switched off for a booth that doesn't need one.
+  Admin config: **PIN** (the switch on the group's title row, 4–8 digits,
+  auto-lock minutes) and **Presets** (quick replies one per line as
+  `Label | Message` — add `| slack:#channel` or `| prodcom:Channel` to bind
+  one to a destination — and up to eight quick emojis).
+  Tile settings: quick emojis on the Send message tile.
 - **Resi Cues** — how long until the next Resi cue point, for a campus
   running video from another site. The tile is one number, as large as it
   will go: the countdown to the next cue, its name above it, and the playhead
@@ -484,7 +508,8 @@ below. Nothing is installed without someone clicking.
   reference for module authors.
 
 To develop modules against mocks instead of real gear:
-`node tools/prodcom-mock.js` (ProdCom on `127.0.0.1:24480`),
+`node tools/prodcom-mock.js` (ProdCom on `127.0.0.1:24480`, including the
+send route the Send Message module uses),
 `node band-lineup-display/tmp/pp-mock.js 1599` (ProPresenter slides on
 `127.0.0.1:1599`), `node tools/pp-timers-mock.js 1600` (ProPresenter
 timers + timecode on `127.0.0.1:1600`), `node tools/pco-mock.js`