feat(maestro): orchestra-themed session-name generator (#23)

New shared `maestro-names` crate producing `adjective-instrument` session
handles drawn from the orchestra pit — musical tempo/dynamics/articulation
markings × instruments and forms (e.g. `allegro-cello`, `crescendo-oboe`,
`staccato-viola`), tying handles to the app's conductor metaphor.

- Pure generation takes an injected RNG; no thread_rng/clock in pure paths,
  so seeded tests are reproducible (repo invariant).
- `generate_unique` prefers the bare name, appending an incrementing numeric
  suffix (`-2`, `-3`, …) only on collision via an injected `is_taken`.
- `generate_thread` is the one impure convenience wrapper for runtime callers.
- Wordlists are public so the web UI can mirror them for instant reroll; the
  Rust generator stays the source of truth.

Closes #23. Part of #21 (spawn dialog rework).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

CLAUDE.md

@@ -24,6 +24,7 @@ crates/
 ├── maestro/             # umbrella binary `maestro` (cli + daemon + registry, feature-gated) (NAP-245)
 ├── maestro-protocol/    # shared wire types (NAP-211)
 ├── maestro-config/      # shared on-disk config schema (NAP-233)
+├── maestro-names/       # orchestra-themed session-handle generator (#23)
 ├── maestro-cli/         # `maestro list/spawn/attach/kill/policy` dispatch (NAP-216)
 ├── maestro-daemon/      # `maestro daemon` — tmux wrapper + WS endpoints (NAP-212, NAP-214)
 ├── maestro-registry/    # `maestro registry` — phone book + HTTP API (NAP-213, NAP-215)