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/protocol.go

@@ -43,6 +43,8 @@ const (
 	OpShutdown            = "shutdown"
 	OpDelete              = "delete"
 	OpGetWorkerStatus     = "get_worker_status"
+	OpGetConfig           = "get_config"
+	OpMolStale            = "mol_stale"
 
 	// Gate operations
 	OpGateCreate = "gate_create"
@@ -558,3 +560,39 @@ type MoleculeProgress struct {
 	Assignee   string         `json:"assignee"`
 	Steps      []MoleculeStep `json:"steps"`
 }
+
+// GetConfigArgs represents arguments for getting daemon config
+type GetConfigArgs struct {
+	Key string `json:"key"` // Config key to retrieve (e.g., "issue_prefix")
+}
+
+// GetConfigResponse represents the response from get_config operation
+type GetConfigResponse struct {
+	Key   string `json:"key"`
+	Value string `json:"value"`
+}
+
+// MolStaleArgs represents arguments for the mol stale operation
+type MolStaleArgs struct {
+	BlockingOnly   bool `json:"blocking_only"`   // Only show molecules blocking other work
+	UnassignedOnly bool `json:"unassigned_only"` // Only show unassigned molecules
+	ShowAll        bool `json:"show_all"`        // Include molecules with 0 children
+}
+
+// StaleMolecule holds info about a stale molecule (for RPC response)
+type StaleMolecule struct {
+	ID             string   `json:"id"`
+	Title          string   `json:"title"`
+	TotalChildren  int      `json:"total_children"`
+	ClosedChildren int      `json:"closed_children"`
+	Assignee       string   `json:"assignee,omitempty"`
+	BlockingIssues []string `json:"blocking_issues,omitempty"`
+	BlockingCount  int      `json:"blocking_count"`
+}
+
+// MolStaleResponse holds the result of the mol stale operation
+type MolStaleResponse struct {
+	StaleMolecules []*StaleMolecule `json:"stale_molecules"`
+	TotalCount     int              `json:"total_count"`
+	BlockingCount  int              `json:"blocking_count"`
+}