Health hypnogram, routes tiles, BB bar chart, segment delta

- Sleep: store per-epoch stage timestamps in new sleep_stages JSON column;
  DailySnapshot now renders a proper 4-lane hypnogram (Awake/REM/Light/Deep)
  instead of the old proportional flat bar
- Body battery: replace grey background bars + white line with per-minute bars
  coloured by inferred type (sleep=indigo, rest=teal, active=orange, stable=grey)
  derived from sleep window + battery direction; Y-axis fixed 0-100
- Routes: convert sidebar list to tile grid sorted by most completions; tiles
  colour-bordered by sport type (blue=running, orange=cycling); completion count
  shown on each tile; detail panel displays below the grid when a tile is clicked
- Segments on activity detail: add column headers (This run / Best / Δ) and
  show signed time delta vs best, green when faster, red when slower

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/app/services/wellness_parser.py

@@ -319,8 +319,10 @@ def parse_wellness_fit(file_path: str) -> dict:
             sleep_rem_s = level_secs[4] or None
             sleep_awake_s = level_secs[1] or None
             sleep_duration_s = (level_secs[2] + level_secs[3] + level_secs[4]) or None
+            sleep_stages = [[int(ts.timestamp() * 1000), level] for ts, level in epochs_sorted]
         else:
             sleep_deep_s = sleep_light_s = sleep_rem_s = sleep_awake_s = sleep_duration_s = None
+            sleep_stages = None
 
         active_cal = data.get("active_calories")
         bmr = data.get("bmr")
@@ -348,6 +350,7 @@ def parse_wellness_fit(file_path: str) -> dict:
             "sleep_score": data.get("sleep_score"),
             "sleep_start": sleep_start_ts,
             "sleep_end": sleep_end_ts,
+            "sleep_stages": sleep_stages,
         }
 
     return {"days": result, "error": None}