feat: Vibration Events sub-tab + last-event on location cards

Two additions to the project Vibration tab:

- Events sub-tab (next to Locations): a project-wide events table across all
  vibration locations. New GET /api/projects/{id}/vibration-events fans
  events_for_location across the project's vibration locations, tags each event
  with its location, and merges newest-first (From/To date filters, Real/FT
  filter, limit). Table columns Timestamp/Location/Serial/Tran/Vert/Long/PVS/
  Mic/Flags; rows open the shared event-detail modal (Chart.js + event-modal.js
  come from the modal partial). Lazy-loads on first open; refreshes on
  sfm-event-review-saved.
- Last event per location card: thread last_event (already in
  events_for_location stats) through the locations endpoint and show
  "Last event: …" on vibration cards.

Reuses the same event source + modal as the per-location Events tab.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

backend/routers/project_locations.py

@@ -160,6 +160,7 @@ async def get_project_locations(
     # (sessions don't really exist for the watcher-forward pipeline).
     # Sound locations skip this and keep showing session counts.
     event_counts: dict[str, int] = {}
+    last_events:  dict[str, str] = {}
     vibration_locations = [l for l in locations if l.location_type == "vibration"]
     if vibration_locations:
         import asyncio
@@ -171,7 +172,10 @@ async def get_project_locations(
         for loc, res in zip(vibration_locations, results):
             if isinstance(res, Exception):
                 continue   # leave event_counts[loc.id] unset → template falls back
-            event_counts[loc.id] = (res.get("stats") or {}).get("event_count", 0) or 0
+            stats = res.get("stats") or {}
+            event_counts[loc.id] = stats.get("event_count", 0) or 0
+            if stats.get("last_event"):
+                last_events[loc.id] = stats["last_event"]
 
     # Enrich with assignment info, splitting active vs removed.
     active_data:  list = []
@@ -205,6 +209,8 @@ async def get_project_locations(
         }
         if location.id in event_counts:
             item["event_count"] = event_counts[location.id]
+        if location.id in last_events:
+            item["last_event"] = last_events[location.id]
         if location.removed_at is None:
             active_data.append(item)
         else:
@@ -1579,6 +1585,70 @@ async def get_project_vibration_summary(
     )
 
 
+@router.get("/vibration-events", response_class=JSONResponse)
+async def get_project_vibration_events(
+    project_id: str,
+    from_dt: Optional[datetime] = Query(None),
+    to_dt: Optional[datetime] = Query(None),
+    false_trigger: Optional[bool] = Query(None),
+    limit: int = Query(500, ge=1, le=5000),
+    db: Session = Depends(get_db),
+):
+    """Project-wide SFM events across every active vibration location.
+
+    Fans out events_for_location per location (each of which unions that
+    location's assignment windows), tags each event with its location, then
+    merges newest-first. Powers the Vibration tab's Events sub-tab.
+    """
+    project = db.query(Project).filter_by(id=project_id).first()
+    if not project:
+        raise HTTPException(status_code=404, detail="Project not found.")
+
+    locations = (
+        db.query(MonitoringLocation)
+        .filter(
+            MonitoringLocation.project_id == project_id,
+            MonitoringLocation.location_type == "vibration",
+            MonitoringLocation.removed_at.is_(None),
+        )
+        .all()
+    )
+    if not locations:
+        return {"events": [], "count": 0, "location_count": 0}
+
+    import asyncio
+    from backend.services.sfm_events import events_for_location
+
+    results = await asyncio.gather(
+        *(
+            events_for_location(
+                db, loc.id, from_dt=from_dt, to_dt=to_dt,
+                false_trigger=false_trigger, limit=limit,
+            )
+            for loc in locations
+        ),
+        return_exceptions=True,
+    )
+
+    merged = []
+    for loc, res in zip(locations, results):
+        if isinstance(res, Exception):
+            continue
+        for ev in res.get("events", []):
+            ev = dict(ev)
+            ev["location_id"] = loc.id
+            ev["location_name"] = loc.name
+            merged.append(ev)
+
+    merged.sort(key=lambda e: e.get("timestamp") or "", reverse=True)
+    total = len(merged)
+    return {
+        "events":         merged[:limit],
+        "count":           total,
+        "location_count":  len(locations),
+    }
+
+
 @router.get("/locations/{location_id}/events", response_class=JSONResponse)
 async def get_location_events(
     project_id: str,