Refactor obsolete extension code

[bartekplus]

Summary

• remove unreachable legacy grammar, text-expander, editor-filler, and settings-engine modules
• replace forwarding wrappers and one-call helper stacks with direct implementations
• remove unused exports, fields, message aliases, and development dependencies
• preserve legacy grammar ID compatibility and migrate Unicode capitalization coverage to the active rule

Verification

• bun run check
• bun run test: 1,512 passed before final Unicode test addition; focused V1 suite 22 passed afterward
• bun run check:e2e:coverage
• bun run build
• bun run build --platform=firefox
• Chrome smoke: 26 passed
• Firefox smoke: 26 passed
• Chrome full: 65 passed, 7 intentional skips
• Firefox full: 65 passed, 7 intentional skips

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-09-13T12:42:50.578200Z	20f4028	PR opened

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