ProdCom 1.5.0: start ProdCom when it is offline, and turn its API on

ProdCom is a sandboxed Mac App Store app whose HTTP API lives inside it,
behind the UserDefaults switch applicationAPIEnabled — absent means off,
and a running ProdCom does not notice the switch changing; it reads it
at launch. So when the tile says "unreachable" on a booth where ProdCom
runs on the same Mac, there are two causes and two fixes: ProdCom is not
running (open it), or it is running with the API off (set the switch,
quit it, open it again).

The module's server now does both, behind two Admin switches, both on:
"Start ProdCom when it is offline" and "Restart ProdCom to turn its API
on". On a connection-level failure (never an HTTP answer) the supervisor
runs up to three attempts five seconds apart: not running → open -g -b;
running with the switch off → write it, read it back, ask ProdCom to
quit (Apple Event, SIGTERM after 5 s), open it again — at most once per
outage; running with the switch on → keep probing, and only blame the
port if that is still true on the third look, because a quitting ProdCom
still shows in pgrep. A successful run nudges the module to reconnect at
once. It gives up with a tile message until ProdCom answers again, and
does nothing at all for a ProdCom on another machine or off macOS.

The launcher gains the Apple Events entitlement and usage string so the
polite quit can be granted; if it is denied, SIGTERM does the job.

Verified live on the dev Mac against ProdCom 2.3.4: not running + switch
absent → opened, switch written, restarted, Live after two attempts; an
operator's Cmd-Q → reopened. 71 fake-driven tests (node --test), the OS
layer included through an injectable execFile.

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

README.md

@@ -358,7 +358,13 @@ below. Nothing is installed without someone clicking.
   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.
+  Admin config: ProdCom server (host : port), API key, and two switches for
+  a ProdCom on this Mac (macOS only): **Start ProdCom when it is offline**
+  opens it when it isn't running (up to three tries, five seconds apart), and
+  **Restart ProdCom to turn its API on** turns the Application API on and
+  restarts ProdCom when it was running with the API off — ProdCom reads that
+  switch only at launch, so the restart costs about ten seconds without
+  intercom. Neither does anything for a ProdCom on another machine.
   Tile settings: channel icons, direction and timestamps.
 - **ProPresenter** — what's live and what's next, with slide progress,
   driven by the shared `propresenter-core` client (ProPresenter 7/20).