docs: update daemon CLI syntax from flags to subcommands

Update all documentation to use the new subcommand syntax:
- `bd daemon --start` → `bd daemon start`
- `bd daemon --stop` → `bd daemon stop`
- `bd daemon --status` → `bd daemon status`
- `bd daemon --health` → `bd daemon status --all`
- `--global=false` → `--local`

The old flag syntax is deprecated but still works with warnings.

Closes: bd-734vd

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

internal/rpc/server_routing_validation_diagnostics.go

@@ -48,7 +48,7 @@ func (s *Server) checkVersionCompatibility(clientVersion string) error {
 		cmp := semver.Compare(serverVer, clientVer)
 		if cmp < 0 {
 			// Daemon is older - needs upgrade
-			return fmt.Errorf("incompatible major versions: client %s, daemon %s. Daemon is older; upgrade and restart daemon: 'bd daemon stop && bd daemon'",
+			return fmt.Errorf("incompatible major versions: client %s, daemon %s. Daemon is older; upgrade and restart daemon: 'bd daemon stop && bd daemon start'",
 				clientVersion, ServerVersion)
 		}
 		// Daemon is newer - client needs upgrade