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>

tests/fixtures/central_envelopes/state_511_atis_08_SH-41.json

@@ -0,0 +1,60 @@
+{
+  "id": "ID:Construction:33655",
+  "source": "central.echo6.co",
+  "type": "central.work_zone.state_511_atis.v1",
+  "time": "2026-05-26T07:32:00+00:00",
+  "datacontenttype": "application/json",
+  "centralschemaversion": "1.0",
+  "centralcategory": "work_zone.state_511_atis",
+  "centralseverity": 1,
+  "specversion": "1.0",
+  "data": {
+    "id": "ID:Construction:33655",
+    "adapter": "state_511_atis",
+    "category": "work_zone.state_511_atis",
+    "time": "2026-05-26T07:32:00Z",
+    "expires": "2026-06-01T18:00:00Z",
+    "severity": 1,
+    "geo": {
+      "centroid": [
+        -116.893994470776,
+        47.8013806004727
+      ],
+      "bbox": null,
+      "regions": [
+        "US-ID"
+      ],
+      "primary_region": "US-ID",
+      "geometry": null
+    },
+    "data": {
+      "roadway_name": "SH-41",
+      "description": "Minor Utility work on SH-41 Southbound near W Boekel Rd. Lane Shift Left. 6/1/2026 7:00 AM to 6/1/2026 6:00 PM Mon: Active all day<div class='cellSpacer'><i><b>Comments:</b></i> Southbound traffic will be shifted to accommodate for Avista to work on power poles. Reduce your speed and lookout for workers on the roadway.</div>",
+      "event_sub_type": "utilityWork",
+      "direction": "South",
+      "location_description": "W Boekel Rd",
+      "county": "Kootenai",
+      "state": "Idaho",
+      "start_date": "6/1/26, 7:00 AM",
+      "last_updated": "5/26/26, 7:32 AM",
+      "is_full_closure": false,
+      "layer": "Construction",
+      "state_code": "ID",
+      "latitude": 47.8013806004727,
+      "longitude": -116.893994470776,
+      "_enriched": {
+        "geocoder": {
+          "name": "American Eagle Automotive",
+          "city": "Rathdrum",
+          "county": "Kootenai",
+          "state": "Idaho",
+          "country": "United States",
+          "postal_code": "83858",
+          "timezone": "America/Los_Angeles",
+          "landclass": null,
+          "elevation_m": 673.84765625
+        }
+      }
+    }
+  }
+}