Fix widespread double JSON encoding bug in daemon RPC calls (bd-1048, bd-4ec8)

Multiple CLI commands had a systematic bug where ResolveID responses were
incorrectly converted using string(resp.Data) instead of json.Unmarshal.
Since resp.Data is json.RawMessage (already JSON-encoded), this preserved
the JSON quotes, causing IDs to become "bd-1048" instead of bd-1048.
When re-marshaled for subsequent RPC calls, these became double-quoted
("\"bd-1048\""), causing database lookups to fail.

Bugs fixed:
1. Nil pointer dereference in handleShow - added nil check after GetIssue
2. Double JSON encoding in 12 locations across 4 commands:
   - bd show (3 instances in show.go)
   - bd dep add/remove/tree (5 instances in dep.go)
   - bd label add/remove/list (3 instances in label.go)
   - bd reopen (1 instance in reopen.go)

All instances replaced string(resp.Data) with proper json.Unmarshal.
Removed debug logging added during investigation.

Tested: All affected commands now work correctly with daemon mode.

internal/rpc/server_routing_validation_diagnostics.go

@@ -103,8 +103,6 @@ func (s *Server) validateDatabaseBinding(req *Request) error {
 }
 
 func (s *Server) handleRequest(req *Request) Response {
-	fmt.Fprintf(os.Stderr, "Debug: handleRequest called for operation: %s (bd-1048)\n", req.Operation)
-	
 	// Track request timing
 	start := time.Now()
 
@@ -112,7 +110,6 @@ func (s *Server) handleRequest(req *Request) Response {
 	defer func() {
 		latency := time.Since(start)
 		s.metrics.RecordRequest(req.Operation, latency)
-		fmt.Fprintf(os.Stderr, "Debug: handleRequest completed for operation: %s in %v (bd-1048)\n", req.Operation, latency)
 	}()
 
 	// Validate database binding (skip for health/metrics to allow diagnostics)