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>

cli/src/i18n.rs

@@ -0,0 +1,60 @@
+//! UI texts (English and German).
+
+use std::sync::atomic::{AtomicBool, Ordering};
+
+static GERMAN: AtomicBool = AtomicBool::new(false);
+
+pub fn set_lang(lang: &str) {
+    GERMAN.store(lang.starts_with("de"), Ordering::Relaxed);
+}
+
+pub fn system_lang() -> String {
+    std::env::var("LC_ALL").or_else(|_| std::env::var("LANG")).unwrap_or_default().chars().take(2).collect()
+}
+
+/// (key, English, German)
+const TEXTS: &[(&str, &str, &str)] = &[
+    ("placeholder", "Message… (/ commands, @ files, Shift+Enter new line)", "Nachricht… (/ Befehle, @ Dateien, Shift+Enter neue Zeile)"),
+    ("busy_placeholder", "Message is queued and sent after this turn…", "Nachricht wird nach diesem Schritt gesendet…"),
+    ("permission", "Permission required", "Freigabe erforderlich"),
+    ("perm_keys", "[y] allow once   [a] always in this session   [n] reject   [f] reject with feedback", "[y] einmal erlauben   [a] immer in dieser Session   [n] ablehnen   [f] ablehnen mit Hinweis"),
+    ("feedback", "Tell the agent what to do instead (Enter to send):", "Was soll der Agent stattdessen tun? (Enter zum Senden):"),
+    ("question", "Question", "Frage"),
+    ("question_keys", "↑↓ choose · Enter confirm · type your own answer · Esc dismiss", "↑↓ wählen · Enter bestätigen · eigene Antwort tippen · Esc verwerfen"),
+    ("thinking", "Thinking", "Denkt nach"),
+    ("working", "Working", "Arbeitet"),
+    ("interrupt", "Esc to interrupt", "Esc unterbricht"),
+    ("mode", "mode", "Modus"),
+    ("context", "context", "Kontext"),
+    ("quit_again", "Press Ctrl+C again to quit", "Nochmal Ctrl+C zum Beenden"),
+    ("aborted", "interrupted", "unterbrochen"),
+    ("no_model", "No model available – run /setup", "Kein Modell verfügbar – /setup ausführen"),
+    ("help", "Commands", "Befehle"),
+    ("choose_model", "Choose a model", "Modell wählen"),
+    ("choose_mode", "Choose a mode", "Modus wählen"),
+    ("choose_session", "Resume a session", "Session fortsetzen"),
+    ("choose_theme", "Choose a theme", "Theme wählen"),
+    ("filter", "type to filter", "tippen zum Filtern"),
+    ("queued", "queued", "in der Warteschlange"),
+    ("welcome", "Welcome to CodeCraft", "Willkommen bei CodeCraft"),
+    ("setup_title", "Set up CodeCraft", "CodeCraft einrichten"),
+    ("setup_intro", "Where should the models come from? You can add more later with /setup.", "Woher sollen die Modelle kommen? Weitere kannst du später mit /setup hinzufügen."),
+    ("setup_server", "Sign in to a CodeCraft server", "Bei einem CodeCraft-Server anmelden"),
+    ("setup_provider", "Add a model provider (API key or local)", "Modell-Anbieter hinzufügen (API-Key oder lokal)"),
+    ("setup_done", "Done", "Fertig"),
+    ("server_url", "Server URL", "Server-Adresse"),
+    ("username", "Username", "Benutzer"),
+    ("password", "Password", "Passwort"),
+    ("api_key", "API key", "API-Key"),
+    ("base_url", "Endpoint URL", "Endpunkt-URL"),
+    ("provider_name", "Name for this provider", "Name für diesen Anbieter"),
+    ("detected", "running locally", "läuft lokal"),
+    ("saved", "Saved.", "Gespeichert."),
+    ("models_found", "models found", "Modelle gefunden"),
+    ("enter_next", "Enter = next · Esc = back", "Enter = weiter · Esc = zurück"),
+];
+
+pub fn t(key: &str) -> &'static str {
+    let de = GERMAN.load(Ordering::Relaxed);
+    TEXTS.iter().find(|(k, _, _)| *k == key).map(|(_, en, d)| if de { *d } else { *en }).unwrap_or("?")
+}