feat(maestro): rename a session from the web sidebar

Right-clicking a card opens a custom context menu (rename, spawn similar,
kill). Rename swaps the name for an inline field; Enter commits, Escape and
blur cancel. The tree stops rebuilding while the field is open, so a catalog
delta cannot replace what is being typed into.

Refs #125

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

web/src/types.ts

@@ -244,10 +244,29 @@ export interface ApiError {
 }
 
 export function sessionName(s: Session): string {
+  return customSessionName(s) ?? s.command;
+}
+
+/** The session's own name, without the command fallback (#125): `undefined`
+ * for a session that was never given one. */
+export function customSessionName(s: Session): string | undefined {
   const meta = s.metadata as Record<string, unknown>;
   const name = meta?.name;
   if (typeof name === "string" && name.length > 0) return name;
-  return s.command;
+  return undefined;
+}
+
+/** Longest session name the daemon stores (#125), in characters. Mirrors
+ * `maestro_protocol::MAX_SESSION_NAME_LEN`. */
+export const MAX_SESSION_NAME_LEN = 64;
+
+/** Trim a requested session name and cap it at {@link MAX_SESSION_NAME_LEN}
+ * characters. Empty means "clear the name", so the card falls back to the
+ * command. Mirrors `maestro_protocol::normalize_session_name` — the daemon
+ * applies the same rule, this only keeps the UI honest about what it will
+ * get back. Uses the spread so the cap counts code points, not UTF-16 units. */
+export function normalizeSessionName(name: string): string {
+  return [...name.trim()].slice(0, MAX_SESSION_NAME_LEN).join("");
 }
 
 /** The directory a session lives in: its live `current_cwd` if the daemon has