Stop one lost extrinsic from silencing the noter bot (#30)

Every report waits behind the previous one, and a submission only settled
when it reached a block. One the pool dropped, rejected or replaced never
settled, so every report queued after it waited forever. The watchdog meant
to catch a silent bot was armed only after the first scan returned, so when
that first scan was the one that hung there was no watchdog at all: the
production container logged its last line one minute after starting on
2026-10-13 and stayed up, silent, for more than a day.

- submit.js: a submission settles on a terminal status (Dropped, Invalid,
  Usurped, FinalityTimeout) or after SUBMIT_TIMEOUT_MS, and releases its
  status subscription.
- The watchdog is armed before connecting and counts from the process start
  until a scan completes, so a heartbeat left by an earlier process in the
  same container does not count for this one.
- The noter's own account is skipped: the chain refuses a noter's report
  about themselves, so it failed in every scan.
- Unit tests for both rules, run inside the noter image in CI.

.github/workflows/ci.yml

@@ -77,6 +77,11 @@ jobs:
       - name: Crypto stack
         run: docker run --rm -v "$PWD/scripts/bot-smoke.mjs:/app/bot-smoke.mjs:ro" bot node bot-smoke.mjs ${{ matrix.mode }}
 
+      # Run inside the image, so the modules under test are the ones the image ships.
+      - name: Unit tests
+        if: matrix.bot == 'noter'
+        run: docker run --rm -v "$PWD/noter/test:/app/test:ro" bot node --test test/submit.test.mjs
+
       - name: The bot loads and stops at its missing mnemonic
         env:
           EXPECT: ${{ matrix.expect }}