Add mj-grunts community pack

[nivaldomcj]

Adds the Michael Jackson Grunts community pack — short vocal grunts and ad-libs mapped across the CESP event lifecycle.

• 18 clips covering all 7 configured categories. Assignment is deliberately non-semantic: these are all grunts, so clips are shuffled and dealt evenly across events (3 each for session.start, task.acknowledge, task.complete, task.error; 2 each for input.required, resource.limit, user.spam) rather than matched to event meaning.
• Source: nivaldomcj/openpeon-mj-grunts @ v1.0.0
• trust_tier: community · license: fair-use (short excerpts; no ownership claimed, rights remain with the respective rights holders) · language: en
• Clips were segmented automatically via ffmpeg silencedetect, deduplicated by MFCC cosine distance, then gated on loudness (RMS >= -40 dB) and spectral flatness (<= 0.06) to drop breaths and broadband noise.
• Entry validates against schema/registry-v1.schema.json ($defs/pack); inserted in alpha order between mizuki and modern-varied; quality field omitted (CI-owned).

Pre-flight (ran the CI gates locally)

• Schema: valid — all 9 required keys present, no keys outside properties (additionalProperties: false).
• Ordering: alphabetical order preserved across all 351 entries; no duplicate names.
• Manifest hash: 868e2426… verified byte-for-byte against the tagged openpeon.json fetched from the public raw URL at v1.0.0.
• Audio limits: 18 files, 448554 bytes total, largest single file 81261 bytes (well under the 1 MB / 50 MB caps); MP3 only.
• Tests: python3 -m unittest discover tests — 43 passed.
• total_packs: bumped 350 → 351 to match len(packs); it was lagging by one before this PR, happy to drop that hunk if you'd rather handle it separately.

🤖 Generated with Claude Code