chore: remove AmazonQ Developer CLI support

[adityadewan22-hub]

The replacement for AmazonQ Developer CLI, Kira CLI is closed source

Changes:

• Removed AmazonQ MCP, rule, and ignore implementations (3 files)
• Removed associated tests(3 files)
• Cleaned up all registrations and references

No replacement is added by design.

Note: local tests fail on Windows due to path separator differences; CI should pass.

[adityadewan22-hub]

This PR addresses #747.

[adityadewan22-hub]

All tests now pass locally. Happy to address any feedback.

[dyoshikawa]

@adityadewan22-hub Thank you!

Additionally, please modify following list:

• Remove "amazonqcli" from src/types/tool-targets.ts
• Remove "amazonqcli" from config-schema.json via running pnpm generate:schema
• Remove Amazon Q related words from cspell.json
• Remove **/.amazonq/ from src/cli/commands/gitignore.ts and run pnpm dev gitignore to update .gitignore in the project
• Remove Amazon Q Developer CLI row from README.md table

[adityadewan22-hub]

Done. Happy to address any feedback.
All checks pass locally as well

[dyoshikawa]

@adityadewan22-hub Thank you, and sorry, you have to resolve conflict.

[dyoshikawa]

@adityadewan22-hub Thank you, please delete .opencode/. Those should not be managed by git.

[dyoshikawa]

Thank you!