feat: add retry option on cancellation/failure screen

[unhappychoice]

close: #128

Summary

• Add retry option to failure and cancellation screens allowing users to restart challenges without exiting the application
• Split monolithic result_screen.rs into focused screen modules for better code organization
• Implement proper retry handling in stage manager with clean navigation flow

Changes Made

New Features

• Failure Screen Retry: Users can press [R] to retry failed challenges
• Cancellation Screen Retry: Users can press [R] to retry cancelled challenges (Ctrl+C or ESC -> Q)
• Seamless Experience: No need to restart the application to retry challenges

Code Refactoring

• Split result_screen.rs into focused modules:
  • failure_screen.rs - Handles failed challenge display and retry
  • cancel_screen.rs - Handles cancelled challenge display and retry
  • session_summary_screen.rs - Session completion and stage results
  • sharing_screen.rs - Social media sharing functionality
• Moved ResultAction enum to centralized location
• Updated all imports and references throughout the codebase
• Applied clippy suggestions for cleaner code

Implementation Details

• Stage Manager Integration: Added proper retry handling in GameState::Failed and GameState::Exit
• Navigation Flow:
  • [R] - Retry the same challenge
  • [T] - Back to title screen
  • [ESC] - Session summary and exit
• Consistent UI: Both screens follow the same interaction pattern as other game screens

Test Plan

• All existing tests pass (147 tests)
• Code compiles without warnings after clippy fixes
• Cargo check, test, clippy, and fmt all pass
• Manual testing of retry functionality on both failure and cancellation scenarios

🤖 Generated with Claude Code

[codecov]

Codecov Report

❌ Patch coverage is 0% with 294 lines in your changes missing coverage. Please review.
✅ Project coverage is 29.45%. Comparing base (05657c3) to head (ff78420).
⚠️ Report is 7 commits behind head on main.

Files with missing lines	Patch %	Lines
src/game/screens/sharing_screen.rs	0.00%	93 Missing ⚠️
src/game/screens/cancel_screen.rs	0.00%	91 Missing ⚠️
src/game/screens/failure_screen.rs	0.00%	73 Missing ⚠️
src/game/stage_manager.rs	0.00%	37 Missing ⚠️

❌ Your patch status has failed because the patch coverage (0.00%) is below the target coverage (80.00%). You can increase the patch coverage or adjust the target coverage.
❌ Your project status has failed because the head coverage (29.45%) is below the target coverage (80.00%). You can increase the head coverage or adjust the target coverage.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #135      +/-   ##
==========================================
- Coverage   29.86%   29.45%   -0.41%     
==========================================
  Files          59       62       +3     
  Lines        8350     8466     +116     
==========================================
  Hits         2494     2494              
- Misses       5856     5972     +116     

Files with missing lines	Coverage Δ
src/game/screens/session_summary_screen.rs	0.00% <ø> (ø)
src/game/stage_manager.rs	0.00% <0.00%> (ø)
src/game/screens/failure_screen.rs	0.00% <0.00%> (ø)
src/game/screens/cancel_screen.rs	0.00% <0.00%> (ø)
src/game/screens/sharing_screen.rs	0.00% <0.00%> (ø)

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