Stage 4: guided Player for both Modes and the Session summary

- buildSegments lays a Plan out as holds with Transitions (get ready,
  switch sides, next round, next exercise) or sets with count-up Rests;
  Supersets alternate members and rest per round unless asked otherwise
- SessionRunner drives segments against an injected clock: auto-advance
  with a chime, pause, skip, back, rep sets confirmed with logged reps
  and kg, timed sets started on demand, early end
- Player screen: countdown ring, accent pulse in the last 3 s, Flip
  Animation, next-up cards, Rest Screen, mute toggle, screen kept on
- Sessions table (schema v2 migration) keeps a Plan snapshot and Set
  Logs; nothing is saved when no hold or set was done
- Summary with time, exercises or sets logged, and every Set Log
- Synthesised quiet cue sounds (tools/sounds), status bar per Mode

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

pubspec.yaml

@@ -7,6 +7,8 @@ environment:
   sdk: ^3.8.1
 
 dependencies:
+  audioplayers: ^6.1.0
+  clock: ^1.1.1
   drift: ^2.31.0
   drift_flutter: ^0.2.8
   flutter:
@@ -17,6 +19,7 @@ dependencies:
   provider: ^6.1.5+1
   shared_preferences: ^2.5.3
   uuid: ^4.6.0
+  wakelock_plus: ^1.4.0
 
 dev_dependencies:
   flutter_test:
@@ -33,6 +36,7 @@ flutter:
   assets:
     - assets/exercises/
     - assets/exercises/images/
+    - assets/sounds/
 
   fonts:
     # Stretching Mode