fix admin delete to wipe originals/edits/geojson; rename button to Reset data

The old DELETE /api/admin/users/{handle}/activities only removed *.json
files and _merged/, leaving originals/ (Strava FIT files) and edits/
untouched — causing the 968 MB disk usage after a delete.

_wipe_user_activities() now removes activities/, edits/, originals/,
_merged/, index.json, athlete.json, and .bincio_cache.json. Admin page
button renamed to "Reset data" with updated confirmation text.

bincio/serve/server.py

@@ -517,38 +517,57 @@ async def admin_rebuild(
     return JSONResponse({"ok": True})
 
 
+def _wipe_user_activities(user_dir: Path) -> int:
+    """Delete all extracted activity files and caches for a user.
+
+    Removes activities/ (JSON + GeoJSON + timeseries), edits/, originals/,
+    _merged/, index.json, athlete.json, and the dedup cache.
+    Leaves the user directory itself intact (account remains in the DB).
+    Returns the number of files deleted.
+    """
+    import shutil
+    deleted = 0
+
+    for subdir in ("activities", "edits", "originals"):
+        d = user_dir / subdir
+        if d.exists():
+            for f in d.rglob("*"):
+                if f.is_file():
+                    deleted += 1
+            shutil.rmtree(d)
+
+    for name in ("_merged", ):
+        d = user_dir / name
+        if d.exists():
+            shutil.rmtree(d)
+
+    for name in ("index.json", "athlete.json", ".bincio_cache.json"):
+        f = user_dir / name
+        if f.exists():
+            f.unlink()
+            deleted += 1
+
+    return deleted
+
+
 @app.delete("/api/admin/users/{handle}/activities")
 async def admin_delete_activities(
     handle: str,
     bincio_session: Optional[str] = Cookie(default=None),
 ) -> JSONResponse:
-    """Delete all activity JSON files for a user and wipe the merged cache."""
+    """Delete all activity data for a user and wipe the merged cache."""
     _require_admin(bincio_session)
     user_dir = _get_data_dir() / handle
     if not user_dir.is_dir():
         raise HTTPException(404, f"No data directory for user '{handle}'")
 
-    deleted = 0
-    activities_dir = user_dir / "activities"
-    if activities_dir.is_dir():
-        for f in activities_dir.glob("*.json"):
-            f.unlink()
-            deleted += 1
-
-    # Wipe merged cache, top-level index, and dedup cache so re-uploads aren't blocked
-    import shutil
-    merged_dir = user_dir / "_merged"
-    if merged_dir.exists():
-        shutil.rmtree(merged_dir)
-    for name in ("index.json", ".bincio_cache.json"):
-        f = user_dir / name
-        if f.exists():
-            f.unlink()
-
+    deleted = _wipe_user_activities(user_dir)
     _trigger_rebuild(handle)
     return JSONResponse({"ok": True, "deleted": deleted})
 
 
+
+
 # ── Write API (ported from bincio edit, auth-gated) ───────────────────────────
 
 def _user_data_dir(handle: str) -> Path: