feat: add download + copy file content to context menus and editor

- Add /api/pages/{id}/download and /api/pages/{id}/file-content endpoints
- Add Download + Copy content to shared context menu (_ctx_menu.html)
- Wire handlers in local-workspace and library context menus
- Add Download + Copy content to editor '...' menu for file pages
- Multi-block selection copy/cut/paste with Ctrl+C/X/V shortcuts
- Align page title with blocks start (CSS pseudo-element offset)

app/routers/dashboard.py

@@ -1021,6 +1021,92 @@ async def get_page_content(page_id: int):
     return {"content": row["content"] or "", "format": fmt}
 
 
+def _file_page_disk_path(page: dict):
+    """Resolve the on-disk file behind a ``content_format == 'file'`` page.
+
+    Returns ``(abs_path: Path, filename: str, mime: str, size: int)`` or None
+    when the row is not a file page, references a non-textual/missing file, or
+    the path escapes the data root (path-traversal guard).
+    """
+    if (page.get("content_format") or "") != "file":
+        return None
+    import json as _json
+    try:
+        meta = _json.loads(page.get("content", "{}"))
+    except (_json.JSONDecodeError, TypeError):
+        meta = {}
+    if not isinstance(meta, dict):
+        return None
+    rel = (meta.get("file_path") or "").replace("\\", "/").strip()
+    if not rel or not rel.startswith("uploads/"):
+        return None
+    parts = rel.split("/")
+    if ".." in parts or "." in parts:
+        return None
+    import os as _os
+    from pathlib import Path
+    root = Path(_os.environ.get("FLOWDECK_DATA_DIR", "/data")).resolve()
+    full = (root / rel).resolve()
+    try:
+        full.relative_to(root)
+    except ValueError:
+        return None
+    if not full.exists() or not full.is_file():
+        return None
+    filename = parts[-1] or page.get("title", "file")
+    mime = meta.get("mime_type") or "application/octet-stream"
+    size = meta.get("size") or 0
+    return (full, filename, mime, size)
+
+
+@router.get("/api/pages/{page_id}/download")
+async def download_page_file(page_id: int):
+    """Download the original uploaded file of a ``file`` page (attachment)."""
+    with get_conn() as conn:
+        row = conn.execute(
+            "SELECT id, title, content, content_format FROM pages "
+            "WHERE id=? AND deleted_at IS NULL",
+            (page_id,),
+        ).fetchone()
+    if not row:
+        return JSONResponse({"error": "Not found"}, status_code=404)
+    resolved = _file_page_disk_path(dict(row))
+    if not resolved:
+        return JSONResponse({"error": "No downloadable file"}, status_code=404)
+    full, filename, mime, _size = resolved
+    from fastapi.responses import FileResponse
+    return FileResponse(
+        str(full), media_type=mime or "application/octet-stream",
+        filename=filename, content_disposition_type="attachment",
+    )
+
+
+@router.get("/api/pages/{page_id}/file-content")
+async def page_file_content(page_id: int):
+    """Return the textual content of a ``file`` page (for copy to clipboard).
+
+    Binary files (PDF, images…) answer ``{ok: false}`` — the clipboard copy is
+    only meaningful for plain-text / code / markdown files.
+    """
+    from app.services.export import _file_text
+    with get_conn() as conn:
+        row = conn.execute(
+            "SELECT id, title, content, content_format FROM pages "
+            "WHERE id=? AND deleted_at IS NULL",
+            (page_id,),
+        ).fetchone()
+    if not row:
+        return JSONResponse({"error": "Not found"}, status_code=404)
+    page = dict(row)
+    text = _file_text(page)
+    if text is None:
+        return JSONResponse(
+            {"ok": False, "error": "Not a textual file", "name": page.get("title", "")},
+            status_code=415,
+        )
+    return {"ok": True, "name": page.get("title") or "File", "content": text}
+
+
 @router.get("/api/local-workspace/breadcrumb")
 async def local_workspace_breadcrumb(request: Request, folder: int):
     """Return breadcrumb trail for a folder."""