Explore: personal GPS heatmap tab under Athlete page

- bincio/explore.py: bake_tracks() simplifies GPS coords (RDP ε=0.0001),
  strips to [lng,lat], groups by sport type, writes per-handle tracks.json
- bake-tracks CLI command; render CLI calls _bake_tracks() after each build;
  strava_zip runs it once at end of batch
- /api/me/tracks endpoint serves the baked file; wipe_user cleans it up
- Explore.svelte: MapLibre full-screen map with sidebar — type pills,
  year/month date filter, Lines / Heatmap (global or by-type) view modes
- AthleteView: Explore tab visible only to profile owner (checks __bincioMe)
- Base.astro: fullscreen prop + Planner nav link

bincio/render/cli.py

@@ -92,6 +92,19 @@ def _merge_edits(data: Path, handle: str | None = None) -> None:
         console.print("No sidecars found — _merged/ dirs mirror extracted data.")
 
 
+def _bake_tracks(data: Path, handle: str | None = None) -> None:
+    """Bake tracks.json for one user or all users."""
+    from bincio.explore import bake_tracks
+
+    targets = [data / handle] if handle else _user_dirs(data)
+    for user_dir in targets:
+        try:
+            n = bake_tracks(user_dir.name, data)
+            console.print(f"  [cyan]{user_dir.name}[/cyan]: {n} track(s) baked")
+        except Exception as exc:
+            console.print(f"  [yellow]{user_dir.name}[/yellow]: bake_tracks failed: {exc}")
+
+
 def _write_root_manifest(data: Path) -> None:
     """Rewrite the root index.json shard manifest from current user dirs."""
     import json
@@ -194,6 +207,7 @@ def render(
     console.print(f"Data:  [cyan]{data}[/cyan]")
 
     _merge_edits(data, handle=handle)
+    _bake_tracks(data, handle=handle)
     _write_root_manifest(data)
 
     if no_build: