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/files.rs

@@ -373,16 +373,35 @@ pub async fn remove(Extension(user): Extension<User>, State(app): State<AppState
 pub struct UploadQuery {
     /// Target file path (absolute).
     path: String,
+    /// Chunked upload: byte offset of this chunk (0 = first chunk, creates the file).
+    offset: Option<u64>,
 }
 
-/// Upload one file as the raw request body.
+/// Upload a file as the raw request body – whole, or in chunks with `offset`
+/// (large files: each chunk stays below the reverse proxy's body limit).
 pub async fn upload(Extension(user): Extension<User>, State(app): State<AppState>, Query(q): Query<UploadQuery>, body: Bytes) -> ApiResult {
     let p = checked_path(&app, &user, &q.path, false)?;
     if p.is_dir() {
         return Err(bad("is a directory"));
     }
-    tokio::fs::write(&p, &body).await?;
-    Ok(Json(json!({"ok": true, "path": p, "size": body.len()})))
+    let max = app.config().server.max_upload_mb.saturating_mul(1024 * 1024);
+    let offset = q.offset.unwrap_or(0);
+    if offset + body.len() as u64 > max {
+        return Err(ApiError(StatusCode::PAYLOAD_TOO_LARGE, format!("file is larger than {} MB", max / 1024 / 1024)));
+    }
+    if offset == 0 {
+        tokio::fs::write(&p, &body).await?;
+    } else {
+        use tokio::io::AsyncWriteExt;
+        let current = tokio::fs::metadata(&p).await.map(|m| m.len()).unwrap_or(0);
+        if current != offset {
+            return Err(ApiError(StatusCode::CONFLICT, format!("chunk offset {offset} does not match the uploaded size {current}")));
+        }
+        let mut f = tokio::fs::OpenOptions::new().append(true).open(&p).await?;
+        f.write_all(&body).await?;
+        f.flush().await?;
+    }
+    Ok(Json(json!({"ok": true, "path": p, "size": offset + body.len() as u64})))
 }
 
 #[derive(Deserialize)]