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/update.rs

@@ -0,0 +1,57 @@
+//! Version information and a daily check for new releases.
+
+use crate::app::App;
+use serde_json::{Value, json};
+use std::sync::{Arc, Mutex};
+use std::time::Duration;
+
+pub const VERSION: &str = env!("CARGO_PKG_VERSION");
+
+/// Git commit the image was built from (Docker build arg GIT_COMMIT).
+pub fn commit() -> &'static str {
+    option_env!("CODECRAFT_COMMIT").unwrap_or("")
+}
+
+#[derive(Default)]
+pub struct UpdateState {
+    pub latest: Mutex<Option<Value>>,
+}
+
+fn newer(a: &str, b: &str) -> bool {
+    let p = |v: &str| v.trim_start_matches('v').split(['.', '-']).take(3).map(|x| x.parse::<u64>().unwrap_or(0)).collect::<Vec<_>>();
+    p(a) > p(b)
+}
+
+async fn check(app: &App) -> Option<Value> {
+    let url = app.config().server.update_url.clone();
+    if url.is_empty() {
+        return None;
+    }
+    let v: Value = crate::provider::http_client().get(&url).timeout(Duration::from_secs(20)).send().await.ok()?.json().await.ok()?;
+    let tag = v["tag_name"].as_str()?.to_string();
+    if !newer(&tag, VERSION) {
+        return None;
+    }
+    Some(json!({"version": tag.trim_start_matches('v'), "url": v["html_url"], "notes": v["body"].as_str().unwrap_or("").chars().take(4000).collect::<String>(), "published_at": v["published_at"]}))
+}
+
+pub fn spawn_checker(app: Arc<App>) {
+    tokio::spawn(async move {
+        tokio::time::sleep(Duration::from_secs(60)).await;
+        loop {
+            let found = check(&app).await;
+            *app.update.latest.lock().unwrap() = found;
+            tokio::time::sleep(Duration::from_secs(24 * 3600)).await;
+        }
+    });
+}
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn version_compare() {
+        assert!(super::newer("v0.2.0", "0.1.9"));
+        assert!(super::newer("1.0.0", "0.9.9"));
+        assert!(!super::newer("v0.1.0", "0.1.0"));
+    }
+}