Add a 'task complete' chime on entering celebrate state

[SnowWarri0r]

Why

The P_CELEBRATE state drives the GIF animation when a turn completes (or on level-up via triggerOneShot), but it's silent. If you're looking at another screen when the buddy starts dancing, you miss it entirely — the visual cue is the only signal.

What

Two-note ascending chime on the transition into P_CELEBRATE, gated by an edge-triggered check on activeState. Note 2 is scheduled via millis() because M5.Beep.tone() is one-at-a-time — calling it twice in the same tick stomps the first note.

static PersonaState prevActiveState = P_SLEEP;
static uint32_t chimeNote2At = 0;
if (activeState == P_CELEBRATE && prevActiveState != P_CELEBRATE) {
  beep(2000, 100);
  chimeNote2At = now + 130;
}
if (chimeNote2At && (int32_t)(now - chimeNote2At) >= 0) {
  beep(2800, 150);
  chimeNote2At = 0;
}
prevActiveState = activeState;

Inserted right after activeState resolves for this tick, so it covers both code paths into celebrate:

1. baseState == P_CELEBRATE driven by recentlyCompleted from the heartbeat (bridge / desktop app)
2. triggerOneShot(P_CELEBRATE, 3000) from statsPollLevelUp()

Design choices

Two notes, not one	The existing single-tone palette (600 Hz deny / 1200 prompt / 1800 cycle / 2400 approve) is dense; a single tone risks sounding like button feedback. An ascending two-note chime is the universal "ta-da" cue for "task complete".
2000 Hz → 2800 Hz	Both new — neither collides with the existing palette. 1.4× ratio reads as "lift" rather than melodic, fitting a short success cue.
100 ms + 130 ms gap + 150 ms	Total ~380 ms, brief enough to not feel intrusive, long enough that the second note registers as distinct rather than a glitch on the first.
Edge-triggered on activeState	One chime per celebrate session (5 s default), not one per loop tick. Catches the level-up triggerOneShot path and the bridge recentlyCompleted path uniformly.
Routes through beep()	Existing settings().sound toggle gates the entire chime (both notes). No new opt-out machinery.

Testing

Flashed on M5StickC Plus (pio run -t upload) and verified live via the Claude Code CLI bridge:

• ✅ Two-note chime fires on every turn-complete heartbeat from the bridge
• ✅ Audibly distinct from the existing 2400 Hz approve confirm — no sonic conflation
• ✅ Animation and chime fire together as a paired audio+visual cue

Edge cases not exercised in this session but covered by the structure:

• Silent operation when Settings → Sound = off (both notes route through beep() which gates on this)
• No re-trigger if triggerOneShot lands while recentlyCompleted is already setting baseState = P_CELEBRATE (single edge transition per celebrate window)

🤖 Generated with Claude Code