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>

scripts/reconcile-schema-after-pgschema.sql

@@ -16,7 +16,6 @@ BEGIN
         -- pgschema may copy parent triggers onto standalone children. Drop
         -- those copies before ATTACH; PostgreSQL recreates inherited parent
         -- triggers while attaching and rejects same-named child triggers.
-        DROP TRIGGER IF EXISTS events_enqueue_push_match ON events_p_past;
         DROP TRIGGER IF EXISTS events_refresh_channel_ttl ON events_p_past;
         DROP TRIGGER IF EXISTS events_created_at_floor ON events_p_past;
         DROP TRIGGER IF EXISTS community_write_fence_events ON events_p_past;
@@ -30,7 +29,6 @@ BEGIN
         WHERE inhparent = 'events'::regclass
           AND inhrelid = 'events_p2026_01'::regclass
     ) THEN
-        DROP TRIGGER IF EXISTS events_enqueue_push_match ON events_p2026_01;
         DROP TRIGGER IF EXISTS events_refresh_channel_ttl ON events_p2026_01;
         DROP TRIGGER IF EXISTS events_created_at_floor ON events_p2026_01;
         DROP TRIGGER IF EXISTS community_write_fence_events ON events_p2026_01;
@@ -44,7 +42,6 @@ BEGIN
         WHERE inhparent = 'events'::regclass
           AND inhrelid = 'events_p2026_02'::regclass
     ) THEN
-        DROP TRIGGER IF EXISTS events_enqueue_push_match ON events_p2026_02;
         DROP TRIGGER IF EXISTS events_refresh_channel_ttl ON events_p2026_02;
         DROP TRIGGER IF EXISTS events_created_at_floor ON events_p2026_02;
         DROP TRIGGER IF EXISTS community_write_fence_events ON events_p2026_02;
@@ -58,7 +55,6 @@ BEGIN
         WHERE inhparent = 'events'::regclass
           AND inhrelid = 'events_p2026_03'::regclass
     ) THEN
-        DROP TRIGGER IF EXISTS events_enqueue_push_match ON events_p2026_03;
         DROP TRIGGER IF EXISTS events_refresh_channel_ttl ON events_p2026_03;
         DROP TRIGGER IF EXISTS events_created_at_floor ON events_p2026_03;
         DROP TRIGGER IF EXISTS community_write_fence_events ON events_p2026_03;
@@ -72,7 +68,6 @@ BEGIN
         WHERE inhparent = 'events'::regclass
           AND inhrelid = 'events_p2026_04'::regclass
     ) THEN
-        DROP TRIGGER IF EXISTS events_enqueue_push_match ON events_p2026_04;
         DROP TRIGGER IF EXISTS events_refresh_channel_ttl ON events_p2026_04;
         DROP TRIGGER IF EXISTS events_created_at_floor ON events_p2026_04;
         DROP TRIGGER IF EXISTS community_write_fence_events ON events_p2026_04;
@@ -86,7 +81,6 @@ BEGIN
         WHERE inhparent = 'events'::regclass
           AND inhrelid = 'events_p2026_05'::regclass
     ) THEN
-        DROP TRIGGER IF EXISTS events_enqueue_push_match ON events_p2026_05;
         DROP TRIGGER IF EXISTS events_refresh_channel_ttl ON events_p2026_05;
         DROP TRIGGER IF EXISTS events_created_at_floor ON events_p2026_05;
         DROP TRIGGER IF EXISTS community_write_fence_events ON events_p2026_05;
@@ -100,7 +94,6 @@ BEGIN
         WHERE inhparent = 'events'::regclass
           AND inhrelid = 'events_p2026_06'::regclass
     ) THEN
-        DROP TRIGGER IF EXISTS events_enqueue_push_match ON events_p2026_06;
         DROP TRIGGER IF EXISTS events_refresh_channel_ttl ON events_p2026_06;
         DROP TRIGGER IF EXISTS events_created_at_floor ON events_p2026_06;
         DROP TRIGGER IF EXISTS community_write_fence_events ON events_p2026_06;
@@ -114,7 +107,6 @@ BEGIN
         WHERE inhparent = 'events'::regclass
           AND inhrelid = 'events_p_future'::regclass
     ) THEN
-        DROP TRIGGER IF EXISTS events_enqueue_push_match ON events_p_future;
         DROP TRIGGER IF EXISTS events_refresh_channel_ttl ON events_p_future;
         DROP TRIGGER IF EXISTS events_created_at_floor ON events_p_future;
         DROP TRIGGER IF EXISTS community_write_fence_events ON events_p_future;