Status LEDs, image model selection, backup restore, provider test, monthly versions

- Sidebar: three status LEDs (server, models, MCP) with an overview popover (/api/status)
- Images: preview stage, purpose-based model choice and reference images
  (Nano Banana Pro edit refines the chosen preview)
- Settings: restore a stored or uploaded backup (staged, applied on restart)
- Provider form: test connection; saving or reloading re-checks the status at once
- opencode Zen/Go: send x-opencode-session with a stable id per conversation
- Releases are named vYYYYMM-NNNNN; scripts/release.sh numbers, tags, builds and publishes
- Fix: backups made in the same second no longer overwrite each other

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

cli/src/server.rs

@@ -19,7 +19,7 @@ pub struct Server {
 
 pub fn http() -> reqwest::Client {
     reqwest::Client::builder()
-        .user_agent(concat!("codecraft-cli/", env!("CARGO_PKG_VERSION")))
+        .user_agent(format!("codecraft-cli/{}", codecraft_core::version::VERSION))
         .connect_timeout(std::time::Duration::from_secs(15))
         .build()
         .expect("http client")