feat(ebuild): add runner args support for flash tools

[BenjaminGuzman]

Summary

Allows developers to pass extra arguments to underlying flash tools (like OpenOCD, esptool, pyOCD) without modifying the ebuild source.

Runner arguments are resolved using the following precedence chain:

1. CLI passthrough
2. Environment variable (EBUILD_FLASH_RUNNER_ARGS)
3. Project configuration

Type of Change

• feat - New feature
• fix - Bug fix
• docs - Documentation only
• style - Formatting, no code change
• refactor - Code restructuring without behavior change
• test - Add or fix tests
• build - Build system or dependency changes
• ci - CI/CD pipeline changes
• perf - Performance improvement

Changes

• Implemented _resolve_runner_args utility function to handle precedence of runner arguments via CLI, Environment, and build.yaml.
• Added support for arbitrary underlying arguments in the flash subcommand using Click's ignore_unknown_options=True context setting.
• Added a --no-runner-args flag to safely and explicitly clear argument overrides.
• Injected resolved arguments correctly for openocd, esptool, pyocd, nrfjprog, and stflash.
• Updated docstring to document the feature.

Testing

• Unit tests pass (ctest --test-dir build --output-on-failure)
  • Note: I noticed that some tests in test_index_sync.py are currently failing on master. It looks like PR fix(packages): validate recipe list fields #112 recently removed the to_dict method from PackageRecipe while index_sync.py still depends on it (fix in PR fix: repair master — the dropped to_dict() fields, vendored drift, scorecard pins (lint landed via #122) #132). My tests suite is passing successfully though.
• Integration tests pass
• Manual testing performed
• New tests added for new functionality

Pre-Submission Checklist

• Code compiles without warnings (-Wall -Wextra -Werror for C)
• All existing tests pass
• New tests added for new functionality
• Documentation updated if API changed
• Commit messages follow the <type>(<scope>): <description> convention
• Branch is rebased on latest master
• This PR links a real issue in this repository with a closing keyword

Related Issue

Closes #162

Screenshots / Logs

Additional Notes

• UX tradeoff: If flash command seamlessly accept unrecognized options, ebuild will no longer throw a "No such option" validation error if a user makes a typo on a native argument (e.g., typing --targt instead of --target). Instead, the typo will be silently consumed and forwarded to the runner tool, which will eventually throw its own error. This is an accepted tradeoff to optimize for the developer experience, but of course I'm also open to change the behavior to be more constrained and less lax.