docs: update all docs for Phase 5 completion with SSH, ctx, themes, detached mode
- phases.md: Phase 5 status -> complete, added SSH/ctx/themes/detached/shiki/updater items, updated file structure
- progress.md: added Phase 5 continued session log, updated next steps
- task_plan.md: added 6 new decisions (ctx read-only, SSH via PTY, themes, detached, shiki), status Rev 3
- CLAUDE.md: added new key paths (ctx.rs, adapters, utils, stores, components), updated deps
- .claude/CLAUDE.md: updated phase status, added new technical constraints
- README.md: updated v2 feature summary
- TODO.md: resolved completed items, added new active items
- CHANGELOG.md: added SSH, ctx, themes, detached, shiki, updater entries
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