feat(content): v0.5.8-state_511_atis -- central_normalizer with Photon nearest_town + composer bypass + SB->S route normalization

First per-adapter content formatter in the meshai-side central_normalizer library (per Central response to schema-divergence + nearest-town reports). state_511_atis (94% of Idaho 511 work-zone traffic) now produces clean wire strings like "🚧 SH-55, near McCall: both directions, emergency repairs" instead of the previous "🚧 ROADS: Work Zone, US-ID. routine -- roadwork".

Implementation: nearest_town(lat, lon) calls Photon directly at 100.64.0.24:2322/reverse with osm_tag=place + client-side filter for city/town/village/hamlet (Navi passthrough route documented in Central response does not exist on current Navi instance). H3-cell-7 LRU cache. Town fallback chain: _enriched.geocoder.city -> nearest_town(coords) -> drop segment. Composer bypass via event.data["_meshai_precomposed"] flag -- renderer owns full wire string for normalized events. SB->S route normalization. distance<1mi -> "near X".

Tests: 535 passed (was 511, +24 net). Synthetic probe over 25 bucket-B + 8 fixture envelopes confirmed 23/25 + 8/8 produce clean output; 2/25 fell back to None (drop segment) on Photon index gaps near Boise/Cascade. Matt eyeballed and approved.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

requirements.txt

@@ -9,6 +9,7 @@ httpx>=0.25.0
 fastembed>=0.3.0
 sqlite-vec>=0.1.0
 numpy
+h3>=4.0
 fastapi>=0.110.0
 uvicorn[standard]>=0.27.0
 aiomqtt>=2.0.0