Add HDFS browser, SSH terminal, presentation editor, lab health panel

- HDFS WebHDFS file browser (api/hdfs_api.py + HdfsView)
- In-browser SSH terminal via paramiko WebSocket bridge (api/ssh_terminal.py + SshTerminal, xterm.js)
- Presentation deck editor (text + image upload) and CRUD endpoints
- Collapsible GPU matrix + new LabHealthPanel in SideNav
- Topology fixes (edge alignment, Hadoop node, compact nodes)
- nginx ws timeout bump for long-lived SSH sessions

api/presentation_upload.py

@@ -163,3 +163,109 @@ def get_deck(deck_id: str) -> dict[str, Any] | None:
     if not path.exists():
         return None
     return json.loads(path.read_text())
+
+
+def _blank_slide(idx: int = 1) -> dict[str, Any]:
+    return {
+        "id": f"slide-{idx}",
+        "title": f"Slide {idx}",
+        "subtitle": "",
+        "bullets": ["Double-click to edit this point"],
+        "image": "",
+        "kind": "narrative",
+    }
+
+
+def create_deck(title: str = "Untitled deck", slides: list[dict[str, Any]] | None = None) -> dict[str, Any]:
+    """Create a new editable deck (optionally seeded from existing slides)."""
+    _ensure_dir()
+    deck_id = str(uuid.uuid4())[:8]
+    deck_dir = PRESENTATIONS_DIR / deck_id
+    (deck_dir / "assets").mkdir(parents=True, exist_ok=True)
+
+    seeded = [dict(s) for s in (slides or [])] or [_blank_slide(1)]
+    payload = {
+        "id": deck_id,
+        "filename": "",
+        "source": "editor",
+        "editable": True,
+        "ts": datetime.now(timezone.utc).isoformat(),
+        "title": (title or "Untitled deck").strip()[:120] or "Untitled deck",
+        "subtitle": "Editable deck",
+        "slide_count": len(seeded),
+        "slides": seeded,
+    }
+    (deck_dir / "meta.json").write_text(json.dumps(payload, indent=2, default=str))
+    (deck_dir / "deck.json").write_text(json.dumps(payload, default=str))
+    return payload
+
+
+def save_deck(deck_id: str, body: dict[str, Any]) -> dict[str, Any] | None:
+    """Overwrite an existing editable deck's content. Returns None if missing."""
+    deck_dir = PRESENTATIONS_DIR / deck_id
+    meta_path = deck_dir / "meta.json"
+    if not meta_path.exists():
+        return None
+    existing = json.loads(meta_path.read_text())
+
+    incoming_slides = body.get("slides")
+    clean_slides: list[dict[str, Any]] = []
+    for i, s in enumerate(incoming_slides or [], start=1):
+        if not isinstance(s, dict):
+            continue
+        bullets = [str(b).strip()[:400] for b in (s.get("bullets") or []) if str(b).strip()]
+        clean_slides.append({
+            "id": str(s.get("id") or f"slide-{i}"),
+            "title": str(s.get("title") or f"Slide {i}")[:200],
+            "subtitle": str(s.get("subtitle") or "")[:300],
+            "bullets": bullets,
+            "image": str(s.get("image") or "")[:300],
+            "kind": str(s.get("kind") or "narrative")[:40],
+        })
+    if not clean_slides:
+        clean_slides = [_blank_slide(1)]
+
+    existing.update({
+        "title": str(body.get("title") or existing.get("title") or "Untitled deck")[:120],
+        "subtitle": str(body.get("subtitle") or existing.get("subtitle") or "")[:300],
+        "editable": True,
+        "source": existing.get("source") or "editor",
+        "ts": datetime.now(timezone.utc).isoformat(),
+        "slides": clean_slides,
+        "slide_count": len(clean_slides),
+    })
+    meta_path.write_text(json.dumps(existing, indent=2, default=str))
+    (deck_dir / "deck.json").write_text(json.dumps(existing, default=str))
+    return existing
+
+
+def delete_deck(deck_id: str) -> bool:
+    import shutil
+    deck_dir = PRESENTATIONS_DIR / deck_id
+    if not deck_dir.exists():
+        return False
+    shutil.rmtree(deck_dir, ignore_errors=True)
+    return True
+
+
+def save_image(deck_id: str, filename: str, content: bytes) -> dict[str, Any] | None:
+    """Store an image in the deck's assets folder; return its served URL."""
+    deck_dir = PRESENTATIONS_DIR / deck_id
+    if not deck_dir.exists():
+        return None
+    assets = deck_dir / "assets"
+    assets.mkdir(parents=True, exist_ok=True)
+    ext = ""
+    if "." in filename:
+        ext = "." + _safe_name(filename.rsplit(".", 1)[-1].lower())[:8]
+    name = f"{uuid.uuid4().hex[:12]}{ext}"
+    (assets / name).write_bytes(content)
+    return {"name": name, "url": f"/api/presentation/decks/{deck_id}/assets/{name}"}
+
+
+def get_asset_path(deck_id: str, name: str) -> Path | None:
+    safe = _safe_name(name)
+    path = PRESENTATIONS_DIR / deck_id / "assets" / safe
+    if not path.exists() or not path.is_file():
+        return None
+    return path