build: pre-deploy HTML inline-script syntax guard

A missing brace in a home.html inline <script> caused an app-wide login
outage (the whole block failed to parse, so boot never ran). Nothing in the
deploy path checked HTML syntax. Add tools/check-syntax.js: parses (never
runs) every inline <script> in server/public/*.html with vm and exits non-zero
on any syntax error, reporting the file + line.

Wired in two places:
- Dockerfile RUN after COPY server/ ./ — a syntax error now FAILS the build,
  so it can't deploy.
- redeploy.sh pre-flight — fast local feedback before triggering the remote
  build.

Verified: passes on current pages (16 blocks / 9 files); fails with the exact
location when a brace is removed.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Dockerfile

@@ -16,6 +16,11 @@ RUN npm install --omit=dev --no-audit --no-fund
 # App source
 COPY server/ ./
 
+# Pre-deploy guard: FAIL the build if any inline <script> in the served HTML pages has a JS syntax error. A
+# broken inline script takes down the whole page (one missing brace in home.html once caused an app-wide login
+# outage). This turns that into a failed build instead of a production incident. See tools/check-syntax.js.
+RUN node tools/check-syntax.js
+
 # Served HTTP port (NPM terminates TLS and proxies here). The DB is Postgres (DATABASE_URL, set via .env);
 # the /data volume holds uploads / recordings / transcripts / downloads (see docker-compose.yml).
 ENV PORT=8090