Add share target, prompt templates, command palette and session organisation

- PWA share target: shared text/links start a new chat or go into a
  recent session (chooser dialog)
- Prompt templates (personal + global for admins) with {{placeholders}}
  that are asked for on insert; managed under Settings → Templates
- Ctrl/Cmd+K command palette; Alt+N new session, Alt+Up/Down switch
  sessions, Ctrl+, settings
- Sessions can be pinned, archived and filed into folders; the list can
  be grouped by date or by project, groups are collapsible
- Fix: the "What's new" dialog was never shown to signed-in users

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

server/src/api.rs

@@ -129,6 +129,8 @@ pub fn router(app: AppState) -> Router {
         .route("/account/git", get(get_git_settings).put(put_git_settings))
         .route("/account/prefs", get(crate::cli_api::get_prefs).put(crate::cli_api::put_prefs))
         .route("/account/memory", get(crate::cli_api::get_memory).put(crate::cli_api::put_memory))
+        .route("/templates", get(crate::cli_api::get_templates))
+        .route("/templates/{scope}", put(crate::cli_api::put_templates))
         .route("/cli/config", get(crate::cli_api::config))
         .route("/cli/skill/{name}", get(crate::cli_api::skill))
         .route("/cli/tool", post(crate::cli_api::tool))
@@ -471,6 +473,9 @@ async fn create_session(Extension(user): Extension<User>, State(app): State<AppS
         clean_room: body.clean_room,
         phase: None,
         worktree: None,
+        pinned: false,
+        archived: false,
+        folder: None,
     };
     let s = app.save_session(s)?;
     Ok(Json(json!(s)))
@@ -617,6 +622,8 @@ async fn fork_session(Extension(user): Extension<User>, State(app): State<AppSta
         last_usage: None,
         phase: None,
         worktree: None,
+        pinned: false,
+        archived: false,
         ..src.clone()
     };
     let fork = app.save_session(fork)?;
@@ -673,10 +680,16 @@ struct UpdateSession {
     agent: Option<String>,
     permission_mode: Option<String>,
     clean_room: Option<bool>,
+    pinned: Option<bool>,
+    archived: Option<bool>,
+    /// "" removes the folder.
+    folder: Option<String>,
 }
 
 async fn update_session(Extension(user): Extension<User>, State(app): State<AppState>, Path(id): Path<String>, Json(body): Json<UpdateSession>) -> ApiResult {
     let mut s = writable(&app, &user, &id)?;
+    // Organising the list must not move the session to "today".
+    let organise_only = body.title.is_none() && body.model.is_none() && body.agent.is_none() && body.clean_room.is_none() && body.permission_mode.is_none();
     if let Some(t) = body.title {
         s.title = t;
     }
@@ -690,6 +703,24 @@ async fn update_session(Extension(user): Extension<User>, State(app): State<AppS
     if let Some(c) = body.clean_room {
         s.clean_room = Some(c);
     }
+    if let Some(p) = body.pinned {
+        s.pinned = p;
+    }
+    if let Some(a) = body.archived {
+        s.archived = a;
+        if a {
+            s.pinned = false;
+        }
+    }
+    if let Some(f) = body.folder {
+        let f = f.trim().chars().take(60).collect::<String>();
+        s.folder = (!f.is_empty()).then_some(f);
+    }
+    if organise_only {
+        app.store.save_session(&s)?;
+        app.emit(Event::SessionUpdated { session: s.clone() });
+        return Ok(Json(json!(s)));
+    }
     if let Some(p) = body.permission_mode {
         if !crate::permission::MODES.contains(&p.as_str()) {
             return Err(ApiError(StatusCode::BAD_REQUEST, "invalid permission mode".into()));