Add Web Push, guided start screen, SVG icons, chunked uploads, rename

- Web Push (VAPID + RFC 8291, pure Rust): permission/question/finished
  notifications while no app window is visible; settings with test button
- Guided new-session flow: task, craft target (website/app/game/old
  software/fresh), clean room or deep, description, model, folder
  (new, existing or cloned git repository); originals upload to original/
- Craft phase bar (craft_phase tool) for study/specify/build/check/ready
- Chunked uploads (8 MB) up to server.max_upload_mb (default 500 MB)
- All UI glyphs and emojis replaced by themeable SVG icons
- Rename dialog with manual name or model-generated suggestion

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

server/src/app.rs

@@ -71,6 +71,8 @@ pub struct App {
     pub shells: crate::shells::Shells,
     /// Language servers (diagnostics after edits).
     pub lsp: crate::lsp::Lsp,
+    /// Web Push (VAPID key, window visibility per user).
+    pub push: crate::push::Push,
 }
 
 /// What a user may do with a session.
@@ -108,6 +110,7 @@ impl App {
             tool_install: Mutex::default(),
             shells: Mutex::default(),
             lsp: Default::default(),
+            push: crate::push::Push::new(&data),
         });
         crate::auth::bootstrap(&app)?;
         app.clone().start_mcp();