chore(push): retire push notification database trigger (#8352)

Buzz must schedule mobile push notifications when it saves an eligible
message. The relay, the server that receives and stores messages, now
does this in application code. An older database trigger still exists.
This trigger is a rule that runs automatically when a message is saved.

This PR removes the old trigger and its supporting database function.
The relay remains responsible for scheduling notifications. Migration
0063 makes this change in existing databases; updated setup scripts
apply it to new databases.

The change does not turn on push notifications. Production migration and
deployment need separate approval. Before deployment, verify the release
images and all pending database migrations. If push needs to be stopped
after release, disable it with the feature flag and keep the qualified
application version and database schema. Do not downgrade the
application image.

### Validation

- Local checks passed: 519 isolated database integration tests, 166
database unit tests, 17 source-policy tests, and the relay push-runtime
tests.
- Tests verify that the migration removes the old trigger, preserves
earlier migration records, and lets the application schedule push work
correctly. A concurrency test exercises the real application path;
deliberately removing its lock makes the test fail.
- [Current-head CI passed on
retry](https://github.com/block/buzz/actions/runs/38752849383/attempts/2).
The first attempt had one database-connection timeout during test setup;
the failed jobs passed when rerun on the unchanged commit.
- Initial local CI and push checks hit unrelated ACP test failures,
which passed when run separately. Only the Rust-test push hook was
skipped under the repository's local-check exception; other applicable
hooks passed.

### Before merge

- [x] Migration 0063 is available and the push trigger remains on [main
at
5397ea4](5397ea49e2).
Recheck if main advances before merge.

---------

Signed-off-by: Tom Brow <tomb@block.xyz>

schema/functions/enqueue_push_match_job.sql

@@ -1,36 +0,0 @@
--- T1b push gate (migrations 0023 and 0059). Enqueue only when the
--- community has an active, endpoint-enabled, unexpired lease; the shared
--- advisory lock pairs with the exclusive lock taken by lease activations
--- (crates/buzz-db/src/push.rs) to close the lost-wake race.
-CREATE FUNCTION enqueue_push_match_job() RETURNS trigger
-LANGUAGE plpgsql AS $$
-BEGIN
-    -- Legacy connections without the setting preserve their existing behavior.
-    -- Updated writer pools always set it, including on reconnect. Check before
-    -- taking push locks or touching leases/queues so disabled chat stays healthy.
-    IF COALESCE(current_setting('buzz.push_async_enqueue', true), '') = 'on' THEN
-        RETURN NEW;
-    END IF;
-    IF NOT COALESCE(NULLIF(current_setting('buzz.push_enabled', true), '')::boolean, true) THEN
-        RETURN NEW;
-    END IF;
-    -- Keep this allowlist identical to the relay's validated NIP-PL descriptor.
-    -- This compatibility path covers legacy writers until they are replaced.
-    IF NEW.kind IN (9, 40002, 45001, 45003) THEN
-        PERFORM pg_advisory_xact_lock_shared(
-            hashtextextended('buzz_push_gate:' || NEW.community_id::text, 0));
-        IF EXISTS (
-            SELECT 1 FROM push_leases
-            WHERE community_id = NEW.community_id
-              AND active
-              AND endpoint_enabled
-              AND expires_at > EXTRACT(EPOCH FROM now())::bigint
-        ) THEN
-            INSERT INTO push_match_queue (community_id, event_id)
-            VALUES (NEW.community_id, NEW.id)
-            ON CONFLICT DO NOTHING;
-        END IF;
-    END IF;
-    RETURN NEW;
-END
-$$;

schema/schema.sql

@@ -64,7 +64,6 @@ CREATE EXTENSION IF NOT EXISTS pgcrypto;
 
 -- functions
 \i functions/channels_community_id_immutable.sql
-\i functions/enqueue_push_match_job.sql
 \i functions/refresh_channel_ttl_after_event_insert.sql
 \i functions/guard_channel_roster_snapshot.sql
 \i functions/events_created_at_floor_guard.sql

schema/triggers/events.sql

@@ -1,7 +1,3 @@
-CREATE TRIGGER events_enqueue_push_match
-AFTER INSERT ON events
-FOR EACH ROW EXECUTE FUNCTION enqueue_push_match_job();
-
 CREATE CONSTRAINT TRIGGER events_refresh_channel_ttl
 AFTER INSERT ON events
 DEFERRABLE INITIALLY DEFERRED