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.

cmd/bd/reopen.go

@@ -30,7 +30,12 @@ This is more explicit than 'bd update --status open' and emits a Reopened event.
 					fmt.Fprintf(os.Stderr, "Error resolving ID %s: %v\n", id, err)
 					os.Exit(1)
 				}
-				resolvedIDs = append(resolvedIDs, string(resp.Data))
+				var resolvedID string
+				if err := json.Unmarshal(resp.Data, &resolvedID); err != nil {
+					fmt.Fprintf(os.Stderr, "Error unmarshaling resolved ID: %v\n", err)
+					os.Exit(1)
+				}
+				resolvedIDs = append(resolvedIDs, resolvedID)
 			}
 		} else {
 			var err error