Refactor: Move sync logic ownership from binary sensor to coordinator

[raman325]

Proposed change

This refactoring addresses the "locks out of sync" issue by centralizing sync operations in the coordinator rather than having them scattered across the binary sensor entity.

Key changes:

Coordinator (coordinator.py):

• Add async_request_sync() to execute set/clear operations with automatic retries
• Add mark_synced() / mark_out_of_sync() for per-slot sync state management
• Add get_sync_state() for binary sensor to read sync status
• Add _pending_retries dict for per-slot retry tracking
• Infinite retries every 10 seconds until success or replaced by new request

Binary sensor (binary_sensor.py):

• Now read-only: displays sync state via is_on property from coordinator
• Detects out-of-sync conditions and requests sync via coordinator
• Removed: _retry_unsub, _retry_active, _schedule_retry, _perform_sync_operation, _cancel_retry - all moved to coordinator

Init (__init__.py):

• Split async_update_listener (~240 lines) into focused helper functions:
  • _ConfigDiff dataclass for computed differences
  • _compute_config_diff(), _setup_new_platforms()
  • _handle_locks_removed(), _handle_locks_added()
  • _handle_slots_removed(), _handle_slots_added()
  • _handle_slots_modified()
• Main function now ~35 lines

Type of change

• Code quality improvements to existing code or addition of tests

Additional information

• This PR fixes or closes issue: fixes #
• This PR is related to issue: Addresses sync reliability concerns from PR review comments

[codecov]

Codecov Report

❌ Patch coverage is 99.31507% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 95.19%. Comparing base (c51f323) to head (32f141d).
⚠️ Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
custom_components/lock_code_manager/__init__.py	98.70%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #730      +/-   ##
==========================================
- Coverage   95.26%   95.19%   -0.07%     
==========================================
  Files          29       29              
  Lines        2384     2414      +30     
  Branches       88       88              
==========================================
+ Hits         2271     2298      +27     
- Misses        113      116       +3     

Flag	Coverage Δ
python	95.05% <99.31%> (-0.08%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
...stom_components/lock_code_manager/binary_sensor.py	96.33% <100.00%> (-1.16%)	⬇️
custom_components/lock_code_manager/coordinator.py	97.36% <100.00%> (+0.44%)	⬆️
custom_components/lock_code_manager/__init__.py	97.24% <98.70%> (+0.35%)	⬆️

... and 1 file with indirect coverage changes

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