docs: refresh for local-first, sync, DID, tables, CMS, and presence

[joepio]

Summary

Public docs lagged the 0.41 local-first release. Spec/protocol pages (websockets.md, Loro commits) were mostly fine; product/GUI docs were thin or missing for the features people actually use now.

This PR drafts the catch-up:

New pages

• Local-first — OPFS/WASM, encryption, offline, relationship to the server
• Sync & pairing — devices vs browser tabs, QR pairing, promote-to-server
• Presence & collaboration — avatars, cursors, follow-me, meetings
• CMS, drafts & forks — visibility-as-location, Fork merge model, websites, i18n

Rewrites / corrections

• Tables — views (kanban/calendar/timer), filters, templates, aggregates, computed columns, LocalizedText, presence
• did.md — remove WIP banner; document pkarr + Iroh as current discovery (Reticulum = planned), not Mainline DHT-as-live
• Forks (commits/suggestions.md) — replace obsolete HTTP Suggestion/Inbox design
• Commits intro — drop “prone to change”; note Loro-only writes
• Overview, feature list, when-to-use, auth examples, sled→redb, 8MB→~70MB, monorepo links
• TOC (SUMMARY.md) + extended modules list
• Planning audit: planning/docs-refresh.md

Deferred (called out in the planning doc)

• @tomic/lib Store / ClientDb deep dive
• React presence hook docs
• Broader atomic-data-browser link sweep

Base branch: develop.