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.

CONTRIBUTING.md

@@ -6,9 +6,10 @@ deliberately high — everything else is ordinary Rust review.
 
 ## Before you start
 
-- Read [`AGENTS.md`](AGENTS.md) for repository conventions and
-  [`docs/ARCHITECTURE.md`](docs/ARCHITECTURE.md) for how the daemon, front ends, and SDK fit
-  together.
+- Read [`AGENTS.md`](AGENTS.md) for repository conventions,
+  [`docs/DEVELOPMENT.md`](docs/DEVELOPMENT.md) for building, running and debugging from source,
+  and [`docs/ARCHITECTURE.md`](docs/ARCHITECTURE.md) for how the daemon, front ends, and SDK fit
+  together. [`docs/README.md`](docs/README.md) indexes the rest.
 - Check [`docs/BUGS.md`](docs/BUGS.md) — it is the authoritative issue ledger, and your problem may
   already be tracked there with context.
 - For anything larger than a fix, open an issue first so the design can be discussed before you
@@ -23,8 +24,9 @@ cargo build --workspace
 ```
 
 GUI and FUSE targets need the GTK4, libadwaita, WebKitGTK 6, libsecret, D-Bus, and FUSE3
-development packages listed in the [README](README.md#prerequisites). Minimum supported Rust
-version is 1.96.
+development packages listed in [`docs/INSTALL.md`](docs/INSTALL.md#build-dependencies). Minimum
+supported Rust version is 1.96. [`docs/DEVELOPMENT.md`](docs/DEVELOPMENT.md#running-from-source)
+explains how to run your build next to, or instead of, the installed service.
 
 ## Quality gates
 
@@ -51,6 +53,13 @@ use a dedicated test account, never one holding data you cannot lose.
   control-socket work stays off GTK's main thread.
 - **`staging/` and `recovery/` may hold the only copy of user data.** Nothing may clear or purge
   them opportunistically.
+- **The GUI is fully translated.** Wrap every user-visible string in the helpers from
+  `crates/pdfs-gui/src/i18n.rs`, run `po/update.sh`, and translate the new entries in every
+  catalog in `po/LINGUAS` in the same change. See [`docs/TRANSLATING.md`](docs/TRANSLATING.md).
+  The CLI and daemon messages stay in English.
+- **Document what users see.** A new command, setting or behaviour belongs in the matching page
+  under `docs/` (user guide, CLI reference or configuration) and in the `[Unreleased]` section of
+  [`docs/CHANGELOG.md`](docs/CHANGELOG.md).
 
 ## Commits and pull requests