Slack module: channel transcript + PIN-gated sending as the location

Each campus signs its booth machine into Slack as the account named for
the location, so a message from ProdDash reads as "Apollo Beach" rather
than as whoever is at the desk. modules/slack (1.0.0) is three tiles from
one module: the live transcript of one channel, a free-text Send tile and
a Quick-replies grid — the last two behind a PIN pad, auto-locking after
a configurable idle time.

Server: one user (xoxp-) or bot (xoxb-) token, identified with auth.test;
conversations.history polled every N seconds (thread replies via
conversations.replies, capped per poll), diffed and fanned out as one
`state` SSE snapshot; mrkdwn rendered to safe text on the server; sends
through chat.postMessage (username/icon for a bot with "Send as"); PIN
compared in constant time with a 5-wrong → 30 s lockout, 32-byte unlock
tokens with a sliding expiry, 1 message/s, every send logged; readable
messages for invalid_auth / token_revoked / missing_scope /
not_in_channel / ratelimited; health reflects token → channel → poll →
sending. SLACK_API_BASE points it at tools/slack-mock.js (new).

Shell: the admin config form gains a multi-line field type `text` (a
textarea; one item per line by convention) — used for the quick replies.
Documented in the module guide; the mock is listed in CLAUDE.md.

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

docs/MODULE-GUIDE.md

@@ -104,7 +104,7 @@ the app); its settings are kept for a later reinstall.
 Both schemas map field names to specs:
 
 ```
-{ "type": "string" | "number" | "boolean" | "switch" | "select" | "color" | "password" | "endpoint",
+{ "type": "string" | "text" | "number" | "boolean" | "switch" | "select" | "color" | "password" | "endpoint",
   "label": "Shown next to the field",
   "default": <value>,
   "group": "Section heading",                         // optional; see below
@@ -125,6 +125,9 @@ shown or enabled, off means hidden or disabled, and the label shouldn't say
 so twice.
 `color` renders a swatch picker and stores a `#rrggbb` string (give it a hex
 default; the tile applies it as a CSS custom property — see `pco-plan`).
+`text` is a multi-line string — a `<textarea>` in the admin page, stored with
+its newlines; one item per line is the convention (the `slack` module's quick
+replies). Admin config only.
 
 `group` gathers consecutive fields under a labeled subsection in the admin
 page, so a module with several distinct concerns (e.g. a ProPresenter