feat: incident correlation overhaul, signal-based auto-resolve, token fixes

Correlator
- Raise fast-path idle gate 30 → 90 min (tg_fast_path_idle_minutes)
- Fix disambiguate always-commits bug: run _call_fits_incident on winner
  before committing; fall through to new-incident creation if it fails
- Add unit-continuity path (path 1.5): matches all_active by shared unit
  IDs with a reassignment guard, bridges calls past the idle gate
- Add tag-based incident_type inference (_TAG_TYPE_HINTS) as GPT fallback,
  rescuing tagged calls that would have been dropped (616 observed orphans)
- Add master/child incident model: _create_master_incident, _demote_to_child,
  _add_child_to_master; new incidents stamped incident_type="master"
- Add cross-system parent detection (_find_cross_system_parent): two-signal
  scoring (road overlap=0.4, embedding≥0.78=0.3, proximity=0.3, threshold=0.5)
  wired into create-if-new path; creates master shell on first cross-system match
- Add maybe_resolve_parent: auto-resolves master when all children close;
  called from upload pipeline (LLM closure) and summarizer stale sweep
- Add signal-based auto-resolve via units_active/units_cleared tracking:
  GPT now extracts cleared_units per scene; _update_incident moves units
  between active/cleared lists and resolves the incident when active empties;
  stored on call doc for re-correlation sweep reuse
- Add _create_incident initialization of units_active/units_cleared fields

Re-correlation sweep
- Add corr_sweep_count + MAX_SWEEP_ATTEMPTS=3: orphans get 3 attempts
  then are tombstoned as corr_path="unlinked", ending the re-sweep loop
  (previously hammering each orphan 29-31 times per shift)

Intelligence extraction
- Add cleared_units to GPT prompt schema and rules
- Extract and propagate cleared_units per scene; merge across scenes;
  store on call doc for re-correlation sweep

Token management
- Fix token release bug: remove release_token call on discord_connected=False
  in MQTT checkin (transient Discord drops were orphaning bots mid-shift)
- Add PUT /tokens/{id}/prefer/{system_id} endpoint: lock a bot token to a
  system; pass _none as system_id to clear; stored bidirectionally on both
  token and system documents
- discord_join handler resolves preferred_token_id from system doc and passes
  system_name in MQTT payload

drb-c2-core/app/internal/intelligence.py

@@ -29,6 +29,7 @@ Response format — a JSON object with a "scenes" array. Each scene:
   location: most specific location string found, or empty string
   vehicles: list of vehicle descriptions mentioned
   units: list of unit IDs or officer numbers explicitly mentioned
+  cleared_units: list of unit IDs that explicitly signal back-in-service or available in this recording
   severity: one of "minor" | "moderate" | "major" | "unknown"
   resolved: true if this scene explicitly signals incident closure, false otherwise
   reassignment: true if dispatch is actively pulling a unit away from their current assignment to respond to a new, different call — e.g. "Baker, can you clear and respond to...", "Adam, break from that and go to...". False if the unit is simply reporting in, updating status, or continuing their current assignment.
@@ -42,6 +43,7 @@ Rules:
 - incident_type: let the talkgroup channel be your primary signal. Use "fire" ONLY if the talkgroup is clearly a fire/rescue channel OR the transcript explicitly describes active fire, smoke, flames, or structure fire activation. Police or EMS referencing a fire scene → use "police" or "ems". When uncertain, prefer "other" over "fire".
 - ten_codes: interpret radio codes using the department reference provided below. Do not guess codes not listed.
 - resolved: true only when the scene explicitly signals "Code 4", "all clear", "10-42", "in custody", "patient transported", "fire out", "GOA", "negative contact", "scene clear".
+- cleared_units: only include units that explicitly stated their own back-in-service status in this recording (e.g. "Unit 7, 10-8", "Baker-1 available", "E-14 back in service", or the department ten-code for available/back-in-service listed above). Silence or absence of a unit is NOT clearance. A scene-wide Code 4 belongs in resolved=true, not here — cleared_units is for individual unit availability signals only.
 - reassignment: only true when a unit is explicitly being pulled to a completely new call or location. A unit going en route to their first dispatch is NOT a reassignment. Routine status updates, acknowledgements, and scene updates are NOT reassignments.
 - transcript_corrected: fix only clear STT/vocoder errors (e.g. "Several" → "10-4", misheard street names, garbled unit IDs). Keep all radio language as-is — do NOT decode codes into plain English. Return null if accurate.
 
@@ -129,6 +131,7 @@ async def extract_scenes(
         location:           Optional[str]  = scene.get("location") or None
         vehicles:           list[str]      = scene.get("vehicles") or []
         units:              list[str]      = scene.get("units") or []
+        cleared_units:      list[str]      = scene.get("cleared_units") or []
         severity:           str            = scene.get("severity") or "unknown"
         resolved:           bool           = bool(scene.get("resolved", False))
         reassignment:       bool           = bool(scene.get("reassignment", False))
@@ -160,6 +163,7 @@ async def extract_scenes(
             "location_coords":      location_coords,
             "vehicles":             vehicles,
             "units":                units,
+            "cleared_units":        cleared_units,
             "severity":             severity,
             "resolved":             resolved,
             "reassignment":         reassignment,
@@ -175,6 +179,7 @@ async def extract_scenes(
     all_tags     = list(dict.fromkeys(t for s in processed for t in s["tags"]))
     all_units    = list(dict.fromkeys(u for s in processed for u in s["units"]))
     all_vehicles = list(dict.fromkeys(v for s in processed for v in s["vehicles"]))
+    all_cleared  = list(dict.fromkeys(u for s in processed for u in s["cleared_units"]))
 
     updates: dict = {"tags": all_tags, "severity": primary["severity"]}
     if primary["location"]:
@@ -183,6 +188,8 @@ async def extract_scenes(
         updates["location_coords"] = primary["location_coords"]
     if all_units:
         updates["units"] = all_units
+    if all_cleared:
+        updates["cleared_units"] = all_cleared
     if all_vehicles:
         updates["vehicles"] = all_vehicles
     if primary["embedding"]: