chore(docker): stamp the API's logs in Asia/Jakarta

The browser sidecar needs a non-UTC zone to clear Cloudflare's challenge,
which left the two services logging on different clocks - the API in UTC,
the sidecar in local time. Correlating a poll failure against anything
else then means doing arithmetic at the worst possible moment.

This is cosmetic and nothing else in the service has a zone. Bookmark
timestamps are unix milliseconds (0001_bookmarks.sql pins that: the
userscripts send Date.now() and the ordering rule compares the integers
directly), the only two real time columns are timestamptz, the poller
works in durations, and nothing anywhere formats a wall clock - there is
no .Format( call in non-test backend code. So the zone can only reach
Go's log package, which stamps lines in local time.

No code change and no image change: distroless/static already carries the
full tzdata (1247 entries, Asia/Jakarta among them), so Go resolves the
name straight out of /usr/share/zoneinfo.

Named API_TZ rather than TZ because compose also reads the invoking
shell's environment, and a bare TZ would let an operator's exported zone
silently become the container's.

Verified against the built image, same instant:

  no TZ            2026/08/08 16:24:30 open store: ...
  TZ=Asia/Jakarta  2026/08/08 23:24:30 open store: ...

matching `date -u` 16:24:33 and Jakarta 23:24:33.

docker-compose.yml

@@ -24,6 +24,13 @@ services:
       # comes from .env so it is never committed.
       DATABASE_URL: ${DATABASE_URL:-postgres://bookmarks:${POSTGRES_PASSWORD:?set POSTGRES_PASSWORD in .env}@postgres:5432/bookmarks?sslmode=disable}
       PORT: "8080"
+      # Log timestamps only. Go's `log` stamps lines in local time, and this
+      # service has no other use for a zone: bookmark timestamps are unix ms
+      # and the two real time columns are timestamptz, both absolute instants.
+      # Purely so these lines read on the same clock as the sidecar's. Named
+      # API_TZ rather than TZ so an operator's exported shell TZ cannot leak
+      # in; distroless already carries tzdata, so the name just resolves.
+      TZ: ${API_TZ:-Asia/Jakarta}
       # Discord OAuth for the browser UI (ADR-0002). The first four are
       # required; DISCORD_REQUIRED_ROLE is optional and empty by default.
       # Guild membership is the whole gate: any member becomes a Reader.