refactor: replace unwrap() with proper error handling in libwayshot

[0xsamalt]

Changes I have made:

• Replaced try_into().unwrap() with a match statement in dispatch.rs to gracefully handle malformed data from the compositor.
• Converted Card::open to return a std::io::Result<Self> and updated its call sites (including lib.rs)
• I have refactored the internal format handling to use direct indexing (state.formats[0]) where values are guaranteed, reducing the reliance on unwrap() while maintaining intended fail-fast behavior for logic bugs.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 0% with 16 lines in your changes missing coverage. Please review.
✅ Project coverage is 16.43%. Comparing base (6f57056) to head (a4252a8).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
libwayshot/src/dispatch.rs	0.00%	15 Missing ⚠️
libwayshot/src/lib.rs	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #294      +/-   ##
==========================================
- Coverage   16.48%   16.43%   -0.05%     
==========================================
  Files          17       17              
  Lines        3197     3206       +9     
==========================================
  Hits          527      527              
- Misses       2670     2679       +9     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[Decodetalkers]

Thank you!