feat(sfm): project-level vibration events roll-up

Phase 3 of the SFM integration. Adds a "Project-wide vibration events"
KPI card to the Vibration tab of every project detail page, summarising
event activity across all of that project's vibration MonitoringLocations.

Backend:
- backend/services/sfm_events.py: vibration_summary_for_project() helper.
  Concurrently fans out events_for_location() across every vibration
  location in the project; aggregates total events, peak PVS (with the
  location it occurred at), last-event timestamp, false-trigger count;
  and produces a per-location breakdown sorted by event count.

- backend/routers/project_locations.py: new GET /api/projects/{p}/
  vibration_summary endpoint returning an HTML partial (HTMX-friendly,
  matches the locations-list HTMX pattern already used on this page).

Frontend:
- templates/partials/projects/vibration_summary.html: new partial with
  four KPI tiles (total, peak PVS + linked location + date, last event,
  false triggers) and a "Top locations by activity" mini-list showing
  the top 5 by event count.  Empty-state copy when the project has no
  vibration locations yet.

- templates/projects/detail.html: HTMX-load the new summary above the
  locations list inside the Vibration tab.

Verified against terra-view-alpha: 24 events across "Loc 1 - 78 poop
street", peak PVS 14.1351 in/s.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

backend/services/sfm_events.py

@@ -414,6 +414,125 @@ async def events_for_unit(
     }
 
 
+# ── Project-level roll-up (aggregates across all vibration locations) ─────────
+
+
+async def vibration_summary_for_project(
+    db: Session,
+    project_id: str,
+    *,
+    from_dt: Optional[datetime] = None,
+    to_dt: Optional[datetime] = None,
+) -> dict:
+    """Aggregate SFM events across every vibration location in a project.
+
+    Returns:
+      {
+        "project_id":  str,
+        "total_events": int,
+        "peak_pvs":     float | None,
+        "peak_pvs_at":  ISO timestamp | None,
+        "peak_pvs_location_id":   str | None,
+        "peak_pvs_location_name": str | None,
+        "last_event":   ISO timestamp | None,
+        "false_trigger_count": int,
+        "per_location": [
+            {"location_id", "location_name", "event_count",
+             "peak_pvs", "last_event"},
+            ...                          # sorted by event_count DESC
+        ],
+        "vibration_location_count": int,
+      }
+    """
+    locations = (
+        db.query(MonitoringLocation)
+        .filter(MonitoringLocation.project_id == project_id)
+        .filter(MonitoringLocation.location_type == "vibration")
+        .all()
+    )
+
+    if not locations:
+        return {
+            "project_id":            project_id,
+            "total_events":           0,
+            "peak_pvs":               None,
+            "peak_pvs_at":            None,
+            "peak_pvs_location_id":   None,
+            "peak_pvs_location_name": None,
+            "last_event":             None,
+            "false_trigger_count":    0,
+            "per_location":           [],
+            "vibration_location_count": 0,
+        }
+
+    # Fan out across locations.  Each call internally fans out across that
+    # location's UnitAssignment rows, so this is a nested fan-out.  Both
+    # tiers happen concurrently because asyncio.gather + httpx pool.
+    results = await asyncio.gather(
+        *(
+            events_for_location(
+                db,
+                loc.id,
+                from_dt=from_dt,
+                to_dt=to_dt,
+                false_trigger=None,
+                limit=1,    # We only need stats; events list itself is ignored.
+            )
+            for loc in locations
+        ),
+        return_exceptions=False,
+    )
+
+    per_location: list[dict] = []
+    total_events = 0
+    peak_pvs = None
+    peak_pvs_at = None
+    peak_pvs_location_id = None
+    peak_pvs_location_name = None
+    last_event = None
+    false_trigger_count = 0
+
+    for loc, res in zip(locations, results):
+        st = res.get("stats", {}) or {}
+        ec = st.get("event_count", 0) or 0
+        total_events += ec
+        false_trigger_count += st.get("false_trigger_count", 0) or 0
+
+        ev_last = st.get("last_event")
+        if ev_last and (last_event is None or ev_last > last_event):
+            last_event = ev_last
+
+        ev_peak = st.get("peak_pvs")
+        if ev_peak is not None and (peak_pvs is None or ev_peak > peak_pvs):
+            peak_pvs = ev_peak
+            peak_pvs_at = st.get("peak_pvs_at")
+            peak_pvs_location_id = loc.id
+            peak_pvs_location_name = loc.name
+
+        per_location.append({
+            "location_id":   loc.id,
+            "location_name": loc.name,
+            "event_count":   ec,
+            "peak_pvs":      ev_peak,
+            "last_event":    ev_last,
+        })
+
+    per_location.sort(key=lambda r: r["event_count"], reverse=True)
+
+    return {
+        "project_id":             project_id,
+        "total_events":            total_events,
+        "peak_pvs":                peak_pvs,
+        "peak_pvs_at":             peak_pvs_at,
+        "peak_pvs_location_id":    peak_pvs_location_id,
+        "peak_pvs_location_name":  peak_pvs_location_name,
+        "last_event":              last_event,
+        "false_trigger_count":     false_trigger_count,
+        "per_location":            per_location,
+        "vibration_location_count": len(locations),
+    }
+
+
 # ── Stats helpers ─────────────────────────────────────────────────────────────