feat: Editor laedt vorhandene Dateien + manueller Code-Toggle (App + Diagnostic)

Editor zeigte "keine Datei", obwohl ARIA schon Dateien geschrieben hatte — er las
NUR den Live-code_file-Stream, nie den Bestand. Jetzt:
- Brain: GET /projects/<id>/files + /file (liest /shared/projects/<id>/, pfad-sicher,
  512KB-Cap). kind in ProjectUpdateBody (PATCH akzeptiert 'code'|'chat').
- App: brainApi.listProjectFiles/readProjectFile/setProjectKind. CodeEditorTile
  holt beim Oeffnen die vorhandene Dateiliste + laedt Inhalt (Live-Version hat
  Vorrang). ProjectsBrowser-Edit: Code-Projekt-Toggle (spiegelt sofort in
  projectFocus → Cockpit-Panels).
- Diagnostic: </> Code-Toggle je Projektzeile + Code-Badge.

py/node/tsc clean.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

aria-brain/main.py

@@ -827,17 +827,73 @@ class ProjectUpdateBody(BaseModel):
     name: Optional[str] = None
     description: Optional[str] = None
     hidden: Optional[bool] = None
+    kind: Optional[str] = None   # 'code' | 'chat' — manuell setzbar (App/Diagnostic)
 
 
 @app.patch("/projects/{project_id}")
 def projects_update(project_id: str, body: ProjectUpdateBody):
     patch = body.dict(exclude_unset=True)
+    if "kind" in patch and patch["kind"] not in ("code", "chat", None):
+        raise HTTPException(status_code=400, detail="kind muss 'code' oder 'chat' sein")
     p = projects_mod.update_project(project_id, patch)
     if p is None:
         raise HTTPException(status_code=404, detail=f"Projekt {project_id} nicht gefunden")
     return p
 
 
+# ── Code-Dateien eines Projekts (/shared/projects/<pid>/) ───────────
+# Der Live-Editor streamt ARIAs Writes; diese Endpoints liefern zusaetzlich die
+# BEREITS vorhandenen Dateien, damit der Editor beim Oeffnen nicht leer ist.
+_PROJECT_FILES_ROOT = "/shared/projects"
+_PROJECT_FILE_MAX = 512 * 1024
+
+
+def _project_dir(project_id: str) -> str:
+    base = os.path.realpath(os.path.join(_PROJECT_FILES_ROOT, project_id or ""))
+    root = os.path.realpath(_PROJECT_FILES_ROOT)
+    if base != root and not base.startswith(root + os.sep):
+        raise HTTPException(status_code=400, detail="ungueltige project_id")
+    return base
+
+
+@app.get("/projects/{project_id}/files")
+def project_files(project_id: str):
+    base = _project_dir(project_id)
+    out = []
+    if os.path.isdir(base):
+        for dirpath, dirs, files in os.walk(base):
+            dirs[:] = [d for d in dirs if d not in
+                       (".git", "node_modules", "__pycache__", ".venv", "venv")]
+            for f in files:
+                full = os.path.join(dirpath, f)
+                rel = os.path.relpath(full, base).replace("\\", "/")
+                try:
+                    sz = os.path.getsize(full)
+                except OSError:
+                    sz = 0
+                out.append({"path": rel, "size": sz})
+    out.sort(key=lambda x: x["path"])
+    return {"projectId": project_id, "files": out}
+
+
+@app.get("/projects/{project_id}/file")
+def project_file(project_id: str, path: str):
+    base = _project_dir(project_id)
+    target = os.path.realpath(os.path.join(base, path))
+    if target != base and not target.startswith(base + os.sep):
+        raise HTTPException(status_code=400, detail="Pfad ausserhalb des Projekts")
+    if not os.path.isfile(target):
+        raise HTTPException(status_code=404, detail="Datei nicht gefunden")
+    if os.path.getsize(target) > _PROJECT_FILE_MAX:
+        raise HTTPException(status_code=413, detail="Datei zu gross fuer den Editor")
+    try:
+        with open(target, "r", encoding="utf-8", errors="replace") as f:
+            content = f.read()
+    except Exception as exc:
+        raise HTTPException(status_code=500, detail=str(exc))
+    return {"projectId": project_id, "path": path, "content": content}
+
+
 @app.get("/conversation/stats")
 def conversation_stats():
     return conversation().stats()