revert: remove fork-only changes from release sync

Revert payment/wechat, sora/claude-max cleanup, fork-only migrations,
and cosmetic changes that were brought in by the release sync commit.
Keep only channel-monitor related improvements:
- PublicSettingsInjectionPayload named struct with drift test
- ChannelMonitorRunner graceful shutdown in wire
- image_output_price in SupportedModelChip
- Simplified buildSelfNavItems in AppSidebar
- Gateway WARN logs for 503 branches

backend/internal/service/ratelimit_session_window_test.go

@@ -73,9 +73,6 @@ func (m *sessionWindowMockRepo) GetByCRSAccountID(context.Context, string) (*Acc
 func (m *sessionWindowMockRepo) FindByExtraField(context.Context, string, any) ([]Account, error) {
 	panic("unexpected")
 }
-func (m *sessionWindowMockRepo) CountByTLSFingerprintProfile(context.Context) (map[int64]int, error) {
-	panic("unexpected")
-}
 func (m *sessionWindowMockRepo) ListCRSAccountIDs(context.Context) (map[string]int64, error) {
 	panic("unexpected")
 }