feat: add daemon RPC endpoints for config and mol stale (bd-ag35)

Add two new RPC endpoints to allow CLI commands to work in daemon mode:

1. GetConfig (OpGetConfig) - Retrieves config values from the daemon database.
   Used by bd create to validate issue prefix in daemon mode.

2. MolStale (OpMolStale) - Finds stale molecules (complete-but-unclosed
   epics). Used by bd mol stale command in daemon mode.

Changes:
- internal/rpc/protocol.go: Add operation constants and request/response types
- internal/rpc/client.go: Add client methods GetConfig() and MolStale()
- internal/rpc/server_issues_epics.go: Add handler implementations
- internal/rpc/server_routing_validation_diagnostics.go: Register handlers
- cmd/bd/create.go: Use GetConfig RPC instead of skipping validation
- cmd/bd/mol_stale.go: Use MolStale RPC instead of requiring --no-daemon
- internal/rpc/coverage_test.go: Add tests for new endpoints

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

internal/rpc/server_routing_validation_diagnostics.go

@@ -225,6 +225,10 @@ func (s *Server) handleRequest(req *Request) Response {
 		resp = s.handleGetMoleculeProgress(req)
 	case OpGetWorkerStatus:
 		resp = s.handleGetWorkerStatus(req)
+	case OpGetConfig:
+		resp = s.handleGetConfig(req)
+	case OpMolStale:
+		resp = s.handleMolStale(req)
 	case OpShutdown:
 		resp = s.handleShutdown(req)
 	// Gate operations