docs: restructure and update documentation for 2.5.0

Split the README into a short front page and task-oriented pages under
docs/: installation, user guide, CLI reference, configuration and
troubleshooting, with an index in docs/README.md. Rewrite RECOVERY.md
around Continue This Backup Here and Restore Folders, and DEVELOPMENT.md
around running, debugging and releasing from source.

Bring ARCHITECTURE.md up to date with the read path, push events, the
thread map, conflict copies and the machine profile, and move the feature
design notes there. Collect planned work in ROADMAP.md. Link the threat
model from SECURITY.md and the translation rules from CONTRIBUTING.md.

Add scripts/publish-wiki.sh, which mirrors the user pages to the GitHub
wiki with rewritten links and only pushes with --push.

docs/CHANGELOG.md

@@ -11,6 +11,17 @@ scratch (user data in `staging/` and `recovery/` is never touched by this).
 
 ## [Unreleased]
 
+### Documentation
+- **Rewritten user documentation.** New pages for installation, the user guide, the command-line
+  reference, configuration and troubleshooting, and a documentation index in `docs/README.md`.
+  The README is shorter and points to them.
+- **Recovery** describes the current restore flow (adopting a computer, `pdfs sync restore`, the
+  machine profile) instead of the old manual runbook.
+- **Architecture** covers push events, remote event streams, the revision block geometry, the
+  thread layout of 2.5.0 and the machine profile. The development page is now a developer guide,
+  and open work moved to `docs/ROADMAP.md`.
+- `scripts/publish-wiki.sh` publishes the user pages to the GitHub wiki.
+
 ## [2.5.0] — 2026-09-28
 
 A polish pass over the desktop app: the daemon pushes changes instead of being polled, pages