Repair stale large channel roster snapshots (#6251)

## Summary

- detect relay-authored NIP-29 kind 39002 roster snapshots truncated by
the former 1,000-member query cap and repair stale large rosters during
relay startup
- serialize canonical roster capture and replacement with membership
writes, preserving tenant, channel, signer, pubkey, and role boundaries
through mixed-version deployments
- install migration 0032's fail-closed roster fence on the partitioned
events table and verify its catalog shape plus behavior before opening
relay listeners

## Rollout

Migration 0032 is a hard schema-before-code compatibility boundary.
Apply migrations before rolling this relay version. Startup refuses to
open listeners when the parent/partition triggers are missing, disabled,
mis-shaped, or behaviorally inert. For large installations, prefer
`buzz-admin migrate` and monitor lock acquisition as documented in the
chart README.

## Validation

Exact head: `bcbba271f54bc0046a6683007e5a2b70403a11d5`

- rebased onto `569308c23c9c2bf620dd3a9a5e4baecbcfa22e16`; the nine-file
feature patch is byte-identical to pre-rebase head
`be8ea0084f4d4c78c7c2550baad4399e4df8ce73`
- pre-push hook passed at exact head: branch-skew, file-size, full Rust
unit suite, Desktop Tauri clippy, and Desktop Tauri tests
- `cargo fmt --all -- --check`
- `cargo test -p buzz-relay
group_members_snapshot_keeps_members_past_one_thousand -- --nocapture`
- focused CI-mode Playwright regression: `selected relay agents revoked
after the invite prompt cause no side effects` passed at exact head
- prior exact-patch validation:
`large_roster_reconciliation_candidates_respect_snapshot_count_and_signer`,
mixed-writer locking/rollback, migration admission, partition trigger
coverage, and desired-schema parity regressions

## Review

Independent DB/relay review found no blocking issues in the exact
feature patch. The concurrency fence holds the established replacement
and membership locks on one transaction/connection through replacement;
failures roll back both soft-delete and insert. Reconciliation remains
tenant/channel/signer scoped and validates exact normalized
pubkey-plus-role membership.

The prior red Desktop shard was unrelated to this backend-only diff: its
mocked mention test exercises no relay, database, or migration path. It
reproduced as a timing flake on the old head, passed on retry/base, and
now passes locally after rebasing onto current main.

---------

Signed-off-by: Wes <wesbillman@users.noreply.github.com>
Co-authored-by: Carl <32a2e2c9d428ee08902cab75d956da2c1d235a22d4766b0dd4138bf6e2e5db1d@buzz.block.builderlab.xyz>

scripts/attach-schema-partitions.sql

@@ -16,12 +16,12 @@ BEGIN
     ) THEN
         -- 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
-        -- (both the push-match trigger and the replica-fence floor guard).
+        -- 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;
+        DROP TRIGGER IF EXISTS trg_events_guard_channel_roster_snapshot ON events_p_past;
         ALTER TABLE events ATTACH PARTITION events_p_past
             FOR VALUES FROM (MINVALUE) TO ('2026-01-01');
     END IF;
@@ -35,6 +35,7 @@ BEGIN
         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;
+        DROP TRIGGER IF EXISTS trg_events_guard_channel_roster_snapshot ON events_p2026_01;
         ALTER TABLE events ATTACH PARTITION events_p2026_01
             FOR VALUES FROM ('2026-01-01') TO ('2026-02-01');
     END IF;
@@ -48,6 +49,7 @@ BEGIN
         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;
+        DROP TRIGGER IF EXISTS trg_events_guard_channel_roster_snapshot ON events_p2026_02;
         ALTER TABLE events ATTACH PARTITION events_p2026_02
             FOR VALUES FROM ('2026-02-01') TO ('2026-03-01');
     END IF;
@@ -61,6 +63,7 @@ BEGIN
         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;
+        DROP TRIGGER IF EXISTS trg_events_guard_channel_roster_snapshot ON events_p2026_03;
         ALTER TABLE events ATTACH PARTITION events_p2026_03
             FOR VALUES FROM ('2026-03-01') TO ('2026-04-01');
     END IF;
@@ -74,6 +77,7 @@ BEGIN
         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;
+        DROP TRIGGER IF EXISTS trg_events_guard_channel_roster_snapshot ON events_p2026_04;
         ALTER TABLE events ATTACH PARTITION events_p2026_04
             FOR VALUES FROM ('2026-04-01') TO ('2026-05-01');
     END IF;
@@ -87,6 +91,7 @@ BEGIN
         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;
+        DROP TRIGGER IF EXISTS trg_events_guard_channel_roster_snapshot ON events_p2026_05;
         ALTER TABLE events ATTACH PARTITION events_p2026_05
             FOR VALUES FROM ('2026-05-01') TO ('2026-06-01');
     END IF;
@@ -100,6 +105,7 @@ BEGIN
         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;
+        DROP TRIGGER IF EXISTS trg_events_guard_channel_roster_snapshot ON events_p2026_06;
         ALTER TABLE events ATTACH PARTITION events_p2026_06
             FOR VALUES FROM ('2026-06-01') TO ('2026-07-01');
     END IF;
@@ -113,6 +119,7 @@ BEGIN
         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;
+        DROP TRIGGER IF EXISTS trg_events_guard_channel_roster_snapshot ON events_p_future;
         ALTER TABLE events ATTACH PARTITION events_p_future
             FOR VALUES FROM ('2026-07-01') TO (MAXVALUE);
     END IF;