feat: add pipeline engine with approval flow and file triggers

Sequential step executor (script, claude_prompt, approval, api_call,
template, skyvern placeholder), reaction-based approvals, file upload
trigger matching, portal API state sync.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

pipelines/steps/skyvern.py

@@ -0,0 +1,24 @@
+"""Skyvern step — browser automation via Skyvern API (Phase 2 placeholder)."""
+
+import logging
+
+logger = logging.getLogger(__name__)
+
+
+async def execute_skyvern(config: dict, send_text=None, target_room: str = "", **_kwargs) -> str:
+    """Dispatch a browser task to Skyvern.
+
+    Phase 2: Will integrate with self-hosted Skyvern on matrixhost.
+    """
+    task = config.get("task", {})
+    url = task.get("url", "")
+    goal = task.get("goal", "")
+
+    if send_text and target_room:
+        await send_text(
+            target_room,
+            f"**Browser Task**: Skyvern integration pending setup.\n"
+            f"URL: {url}\nGoal: {goal}",
+        )
+
+    raise NotImplementedError("Skyvern step not yet implemented (Phase 2)")