feat(research): add keyword workspace actions

[hubab1]

Summary

• add exact-generation keyword membership browsing, pagination, creation, and removal to the research project workspace
• expose independent shared search-evidence and popularity refresh actions with structured disposition, provenance, and redacted recovery states
• retain project detail models across navigation and sheet reopen, serialize destructive UI, and recover committed-but-unpublished mutations without retrying them
• focus the Apple Ads web-session settings section for authentication recovery

Validation

• 6 focused tests passed across KeywordResearchKeywordSelectionTests and KeywordResearchModelFactoryTests
• 450 full-suite tests passed on macOS arm64
• signed Debug build succeeded
• codesign --verify --deep --strict passed
• git diff --check and project-file validation passed

Review notes

• draft for manual workspace UX review before merge
• no live persistent-store launch was performed on this schema stack
• depends on feat(research): add project workspace shell #56