Add terminal client, memory, model fallback, version and install improvements

- codecraft: full-screen terminal client (ratatui) – local tools and files,
  models via the CodeCraft server gateway or own providers (standalone with a
  guided setup), slash commands, @files, permission dialogs, resume, update
- Static Linux CLI builds (x86_64/aarch64, cargo-zigbuild) served by the
  server: /cli/install.sh and /cli/download/<target>
- Project memory (remember tool, .codecraft/memory.md) and personal memory
- Model fallback when a host is unreachable or a budget is used up
- Version/commit in UI and health, daily release check, "What's new" dialog
- PWA: install button, maskable icon, manifest id and screenshots
- Case-insensitive detection of connection errors for retries

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

config.example.toml

@@ -187,6 +187,7 @@ web_fetch = "ask"
 web_search = "allow"
 diagnostics = "allow"
 openscad = "allow"     # renders .scad files to STL/3MF + previews
+remember = "allow"     # project memory (.codecraft/memory.md)
 browser_snapshot = "allow"
 image_compare = "allow"
 generate_image = "ask"   # costs money per image