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>

server/src/app.rs

@@ -77,6 +77,8 @@ pub struct App {
     pub push: crate::push::Push,
     /// Web terminals (PTYs).
     pub terminals: crate::terminal::Terminals,
+    /// Newer release found by the update check (admins see it).
+    pub update: crate::update::UpdateState,
 }
 
 /// What a user may do with a session.
@@ -116,6 +118,7 @@ impl App {
             lsp: Default::default(),
             push: crate::push::Push::new(&data),
             terminals: Default::default(),
+            update: Default::default(),
         });
         crate::auth::bootstrap(&app)?;
         app.clone().start_mcp();