fix(plugin): stop CI installing the jq the hooks no longer use (#4107)

Three loose ends from a49e7ed, all found by CI or by re-reading it.

TWO TESTS PINNED THE jq SYNTAX, not the word `jq`, so grepping the suite for
the tool name missed them: test_write_path_trigger asserted the literal filter
strings `(.note_ids // []) - (.sync_note_ids // [])` and `(.rule_ids // [])[]?`
appear in the hook. Re-spelled with the readers that replaced them. The claim
each makes is unchanged — that the reuse and sync channels keep their own
state file, their own query parameter and their own write-back.

CI STILL INSTALLED jq, TWICE. The "Install jq for hook execution tests" step
existed because those tests skipped rather than failed without it; the Plugin
hooks job installed it alongside shellcheck for the same reason. Removing a
dependency from the product and leaving CI to install it anyway means the
smoke tests never run under the condition they exist to assert. Both gone —
the hook tests now run on a bare image.

`awk 'END { print $0 }'` IS UNDEFINED IN POSIX. gawk retains the last record
in END and mawk does too, but it is not guaranteed, and reaching for a
non-portable idiom inside the change whose entire purpose is portability is
the same mistake one layer down. Now `{ last = $0 } END { if (NR) print last }`.
Verified it still selects the same start line on a real transcript.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01821k5B3Ysecp9fNYs92Kuy

.forgejo/workflows/ci.yml

@@ -111,7 +111,7 @@ jobs:
 
   # Guards the one part of this repo that ships to users without a build step.
   # See scripts/check_plugin.py for what it checks and, as importantly, what it
-  # can't check yet (shellcheck and jq are absent from ci-python).
+  # can't check yet (shellcheck is absent from ci-python).
   plugin:
     name: Plugin hooks
     if: github.ref == 'refs/heads/dev' || github.ref == 'refs/heads/main' || startsWith(github.ref, 'refs/tags/v')
@@ -133,12 +133,15 @@ jobs:
       # the only consumer today. Promotion into ci-python is filed as an issue
       # on CI-runner rather than assumed here.
       #
-      # jq is not optional for the smoke test: every hook exits at line 1
-      # without it, so the check would pass while exercising nothing.
+      # jq WAS installed here too, because every hook exited at line 1 without
+      # it and the smoke test would have passed while exercising nothing. The
+      # hooks need no jq since #4107 — they use only what POSIX guarantees — so
+      # the smoke test now runs on a bare image, which is the condition it is
+      # actually meant to be asserting.
       - name: Install shell tooling
         run: |
           apt-get update -qq
-          apt-get install -y -qq --no-install-recommends jq shellcheck
+          apt-get install -y -qq --no-install-recommends shellcheck
 
       # On main the comparison would be against itself, so only the syntax and
       # pattern checks mean anything there.
@@ -223,16 +226,12 @@ jobs:
           UV_PROJECT_ENVIRONMENT: /opt/venv
         run: uv sync --locked --extra dev
 
-      # The hook-EXECUTION tests (test_write_path_trigger's nudge pair) run the
-      # real bash hook, which exits silently without jq — and those tests skip
-      # rather than fail when it's absent, so without this step they would
-      # quietly never be verified anywhere (ci-python ships without jq; same
-      # install the Plugin hooks job does).
-      - name: Install jq for hook execution tests
-        run: |
-          apt-get update -qq
-          apt-get install -y -qq --no-install-recommends jq
-
+      # An "Install jq for hook execution tests" step stood here. The hook
+      # EXECUTION tests run the real bash hook, which exited silently without
+      # jq and skipped rather than failed, so the step existed to stop them
+      # being silently unverified. Since #4107 the hooks need no jq, so the
+      # step is gone and those tests run against a bare image — and the point
+      # of removing a dependency is lost if CI keeps installing it anyway.
       - name: Run tests
         # Integration tests (real Postgres) run in the `integration` job below.
         run: /opt/venv/bin/python -m pytest tests/ -q -m "not integration"