enhancement: catch errors and prevent early exit in build

[soulcodingmatt]

Task

Improve error handling in the annotation processor build lifecycle to catch errors gracefully and prevent early exit that could hide useful diagnostic information.

Parent epic: #19

Details

Currently, certain error conditions during annotation processing cause the build to exit early, potentially hiding subsequent errors or warnings that would help developers understand what went wrong. The processor should catch errors, collect diagnostics, and report them all at the end of the processing round.

Acceptance Criteria

• Errors during generation do not cause immediate processor exit
• All errors are collected and reported at the end of the processing round
• The build still fails with a clear summary of all errors
• Existing tests continue to pass