Document the July batch in the changelog and README

Changelog entries for the Live Activity, mid-workout library adds,
backups, diagnostics, watch-only Health recording, navigation and
accessibility improvements, and the bug fixes; README key features
updated to match.

Claude-Session: https://claude.ai/code/session_01HJDQQDA9QdP8zByg43H5v3

README.md

@@ -25,7 +25,12 @@ your own iCloud Drive.
   a **Finish** page — mirroring the Apple Watch. Swipe a row to mark it complete, or
   swipe to edit its plan (sets/reps/weight or duration) and notes. End a workout early
   from the **⋯** menu — **Save** keeps your progress (remaining exercises are marked
-  skipped) or **Discard** removes it.
+  skipped) or **Discard** removes it. Mid-workout, add any exercise from the full
+  library — its plan is seeded from your most recent session with it, or from the
+  library's authored defaults.
+- **Live Activity** — the running workout lives on the Lock Screen and in the
+  Dynamic Island: current exercise, set count, phase, and a live rest countdown,
+  updating through every transition without unlocking the phone.
 - **Animated form guide** — every library exercise shows a looping stick-figure
   demonstration on the run screen's bottom half, posed by real joint angles on an
   anatomical 3D skeleton (complete with feet) and rendered live from the Exercise
@@ -53,14 +58,20 @@ your own iCloud Drive.
 - **Watch face complication** — a launcher complication you can place on any Apple
   Watch face; tap it to open the app. Available in the circular, corner, inline, and
   rectangular accessory slots.
-- **Apple Health & Activity rings** — completed workouts are saved to Apple Health
-  and credit your Move and Exercise rings: recorded live on the Apple Watch (heart
-  rate + active energy), or estimated on the iPhone when you train without your
-  watch. See live heart rate and calories on the watch, and a post-workout summary
-  (duration, calories, avg/max heart rate, heart-rate zones, total volume) you can
-  revisit on any past workout. Weights display in your choice of pounds or kilograms.
+- **Apple Health & Activity rings** — workouts recorded on the Apple Watch (heart
+  rate + active energy) are saved to Apple Health and credit your Move and Exercise
+  rings. See live heart rate and calories on the watch, and a post-workout summary
+  (duration, calories, avg/max heart rate, heart-rate zones with a legend, total
+  volume) you can revisit on any past workout. Weights display in your choice of
+  pounds or kilograms.
 - **iCloud Drive sync** — your data lives as human-readable JSON in your iCloud
   Drive, synced across devices and visible in the Files app. iCloud is required.
+- **Backups** — create point-in-time snapshots of all your data from Settings,
+  keep several with retention controls, and restore one with a tap (backup files
+  open straight into the app).
+- **Diagnostics** — a Settings screen that shows iCloud account and container
+  status, per-document download/eviction state, schema compatibility, and network
+  readiness — with a one-tap copyable report.
 
 ## Architecture