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/gemini_multiplatform_test.go

@@ -71,10 +71,6 @@ func (m *mockAccountRepoForGemini) FindByExtraField(ctx context.Context, key str
 	return nil, nil
 }
 
-func (m *mockAccountRepoForGemini) CountByTLSFingerprintProfile(ctx context.Context) (map[int64]int, error) {
-	return nil, nil
-}
-
 func (m *mockAccountRepoForGemini) ListCRSAccountIDs(ctx context.Context) (map[string]int64, error) {
 	return nil, nil
 }