feat(notifications): Phase 2.8 roads511 adapter pipeline integration

Adds Roads511Adapter.to_event(), wiring the state 511 road-events adapter
into the notification EventBus following the Phase 2.7 traffic pattern.

to_event() design:
- Category: fixed "road_closure".
- Severity: passed through unchanged from the adapter's existing
  _parse_event logic (priority on closure, else routine).
- Summary enriched with closure status, roadway, and description.
- group_key: the stored event_id (already the stable "511_{id}" key), so
  re-polls of the same incident coalesce.
- inhibit_keys: a single key equal to group_key. Severity tiering is
  delegated to the pipeline Inhibitor (ranks routine<priority<immediate
  per shared key, suppressing lower-severity re-emissions of the same
  incident within the Inhibitor TTL). No severity encoded into the key.
- Defensive: missing lat/lon or missing event_id returns None; whole body
  is try/except-guarded (returns None on corruption).

Store wiring: no change. EnvironmentalStore._ingest()'s generic "else"
branch already emits any adapter exposing to_event() (live since 2.6.5).

Rule 17: to_event introduces no new tunable. (The state base_url / bbox /
api_key already exist in Roads511Config and env_feeds.yaml; secrets go in
/data/secrets/.env via ${VAR}, never git.)

Tests: tests/test_adapter_roads511.py (14 tests) mirrors
test_adapter_traffic.py -- category, severity pass-through,
group_key/inhibit_keys, field population, defensive cases. Full suite:
161 passed.

live smoke test SKIPPED: Idaho 511 v2 (511.idaho.gov/api/v2) requires an
API key ("Invalid Key" response) and none is available in .ref/credentials
(cannot self-register). Per the standing key-less-adapter policy, the code
+ unit tests are committed and Gate D is skipped; roads511 is left disabled
in prod (enabling it keyless would only emit HTTP 400 errors). The
to_event() path is fully unit-validated and structurally identical to the
live traffic/FIRMS wiring (same EnvironmentalStore->EventBus path); live
validation will run if/when an Idaho 511 key is provided.

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

meshai/env/roads511.py

@@ -8,11 +8,13 @@ import json
 import logging
 import os
 import time
-from typing import TYPE_CHECKING
+from typing import TYPE_CHECKING, Optional
 from urllib.error import HTTPError, URLError
 from urllib.request import Request, urlopen
 from urllib.parse import urljoin
 
+from meshai.notifications.events import Event, make_event
+
 if TYPE_CHECKING:
     from ..config import Roads511Config
 
@@ -348,6 +350,64 @@ class Roads511Adapter:
             logger.debug(f"511 event parse error: {e} - item: {item}")
             return None
 
+    def to_event(self, evt: dict) -> Optional["Event"]:
+        """Translate a stored 511 road event dict into a pipeline Event.
+
+        Args:
+            evt: Internal event dict from get_events()
+
+        Returns:
+            Event instance ready for EventBus emission, or None if the
+            dict is missing required fields (lat/lon or event_id).
+        """
+        try:
+            lat = evt.get("lat")
+            lon = evt.get("lon")
+            if lat is None or lon is None:
+                return None  # Can't make a useful Event without coords
+
+            event_id = evt.get("event_id")
+            if not event_id:
+                return None  # No stable identity to group/inhibit on
+
+            props = evt.get("properties", {}) or {}
+            severity = evt.get("severity", "routine")
+            title = evt.get("headline", "") or evt.get("event_type", "") or "Road Event"
+
+            # Richer summary: closure status, roadway, description
+            summary_parts = [title]
+            if props.get("is_closure"):
+                summary_parts.append("road closed")
+            roadway = props.get("roadway")
+            if roadway and str(roadway) not in title:
+                summary_parts.append(str(roadway))
+            desc = evt.get("description")
+            if desc and desc not in title:
+                summary_parts.append(desc)
+            summary = " | ".join(summary_parts)[:300]
+
+            # The stored event_id is already the stable "511_{id}" key. Re-polls
+            # of the same incident coalesce on this group_key; using it as the
+            # sole inhibit_key lets the pipeline Inhibitor suppress
+            # lower-severity re-emissions while a higher-severity one is active
+            # for the same incident (severity tiering delegated to Inhibitor).
+            return make_event(
+                source="511",
+                category="road_closure",
+                severity=severity,
+                title=title,
+                summary=summary,
+                timestamp=evt.get("fetched_at"),
+                expires=evt.get("expires"),
+                lat=lat,
+                lon=lon,
+                group_key=event_id,
+                inhibit_keys=[event_id],
+            )
+        except Exception:
+            logger.exception(f"511 to_event failed for evt: {evt.get('event_id')}")
+            return None
+
     def get_events(self) -> list:
         """Get current road events."""
         return self._events