area_context v2 + Maps place verification (server-26#36, #37)

#36 — the correction pass shipped in 58efdbd was right, its reference-data
shape was not. One shape now, at both scopes, every field nullable:

  area_context: { municipality?, county?, state?,
                  center?, radius_km?, resolved_from?, resolved_at?,
                  local_knowledge?: [{term, meaning}] }

`state` closes the ambiguity that made "Ossining" a national guess.
`local_knowledge` replaces roads[]/landmarks[], which could not hold
intersections, schools or nicknames and carried no meanings — `11-X-ray` is
useless alone, `11-X-ray — MTA PD patrol unit` is what a corrector can act on.
Pre-#36 roads[]/landmarks[] are read forward as bare terms so nothing an
operator already entered is lost.

Nullability is the mechanism: which scope gets filled is the operator's
declaration of how homogeneous the system is. One town — fill it once at system
level. Statewide — leave it blank and fill each talkgroup.

The backend owns the derived anchor. PUT /systems/{id} merges config.talkgroups[]
against what is stored instead of writing the client's blob verbatim, which
would have erased the anchor and the pending queue — the same defect as the
ten_codes wipe.

#37 — Maps as a verifier, not as prompt stuffing. The corrector emits its
location nouns; each is geocoded against the talkgroup's anchor, and on a miss
we look for a sound-alike that does resolve there, correct to it, and propose
{term, meaning} to that talkgroup. Cost scales with location nouns, not calls.

No anchor means SKIP. An area too wide to discriminate stores no anchor at all,
because a statewide radius would confirm anything inside it — verification that
passes everything is worse than none, since it reads as a check in the data.

Also re-anchors _geocode_location, which rejected results >40km from the NODE
(server-26#6). An antenna is not a jurisdiction; distance-from-node was always
a stand-in for the anchor and is now only the fallback.

The induction loop proposes at talkgroup level and never promotes. Blast
radius: a wrong term on a channel misleads that channel, the same term
system-wide misleads one 400km away on a statewide system.

38 new tests; 240 pass. Frontend typechecks clean.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

drb-frontend/lib/types.ts

@@ -237,9 +237,40 @@ export interface AlertEvent {
  * a multi-county system can be specific per channel without its wider list
  * burying the detail.
  */
+export interface LocalKnowledgeEntry {
+  term: string;
+  meaning?: string | null;
+}
+
 export interface AreaContext {
+  // Set by an operator. Every field nullable on purpose: which SCOPE gets
+  // filled is the declaration of how homogeneous the system is. A one-town
+  // system is described once here and inherited by every talkgroup; a
+  // statewide one is left empty here and described per talkgroup.
   municipality?: string;
   county?: string;
-  roads?: string[];
-  landmarks?: string[];
+  state?: string;
+  local_knowledge?: LocalKnowledgeEntry[];
+  // Written by the backend, read-only here. Absent means the place is unset or
+  // too wide to discriminate, and location verification skips entirely
+  // (server-26#37) — never send these back.
+  center?: { lat: number; lng: number };
+  radius_km?: number;
+  resolved_from?: string;
+  resolved_at?: string;
+}
+
+/** A term the verifier or the induction loop proposed for one talkgroup. */
+export interface PendingLocalTerm {
+  term: string;
+  meaning?: string | null;
+  source: string;
+  added_at: string;
+  source_call_ids?: string[];
+}
+
+export interface TalkgroupPending {
+  talkgroup_id: number;
+  talkgroup_name?: string;
+  pending: PendingLocalTerm[];
 }