fix mid level issues. updated changelog

SCHEMA.md

@@ -82,7 +82,7 @@ needed to render an activity card in a feed — no timeseries, no full track.
 
 ```json
 {
-  "id": "2024-06-01T073012+0200-morning-ride",
+  "id": "2024-06-01T073012Z-morning-ride",
   "title": "Morning Ride",
   "sport": "cycling",
   "sub_sport": "road",
@@ -99,8 +99,8 @@ needed to render an activity card in a feed — no timeseries, no full track.
   "avg_power_w": null,
   "source": "strava_export",
   "privacy": "public",
-  "detail_url": "activities/2024-06-01T073012+0200-morning-ride.json",
-  "track_url": "activities/2024-06-01T073012+0200-morning-ride.geojson"
+  "detail_url": "activities/2024-06-01T073012Z-morning-ride.json",
+  "track_url": "activities/2024-06-01T073012Z-morning-ride.geojson"
 }
 ```
 
@@ -137,13 +137,13 @@ The canonical ID format is:
 ```
 
 Where `started_at_compact` is the start timestamp with special characters
-removed: `2024-06-01T073012+0200`, and `slug` is an optional URL-safe
+removed: `2024-06-01T073012Z`, and `slug` is an optional URL-safe
 lowercase title (spaces → hyphens, non-ASCII stripped).
 
-Example: `2024-06-01T073012+0200-morning-ride`
+Example: `2024-06-01T073012Z-morning-ride`
 
 IDs must be unique within a data store. When a title is unavailable, the
-timestamp alone is sufficient: `2024-06-01T073012+0200`.
+timestamp alone is sufficient: `2024-06-01T073012Z`.
 
 ### Source values
 
@@ -177,7 +177,7 @@ Full activity record. Extends the Summary with timeseries and metadata.
 ```json
 {
   "bas_version": "1.0",
-  "id": "2024-06-01T073012+0200-morning-ride",
+  "id": "2024-06-01T073012Z-morning-ride",
   "title": "Morning Ride",
   "description": "Easy morning spin before work.",
   "sport": "cycling",
@@ -297,7 +297,7 @@ Simplified GPS track for map rendering. Omitted entirely when
     ]
   },
   "properties": {
-    "id": "2024-06-01T073012+0200-morning-ride",
+    "id": "2024-06-01T073012Z-morning-ride",
     "speeds": [0.0, 15.2],
     "simplification": "rdp",
     "rdp_epsilon": 0.0001,