refactor(runtime): restructure runs module with new execution architecture

Major refactoring of deerflow/runtime/:
- runs/callbacks/ - new callback system (builder, events, title, tokens)
- runs/internal/ - execution internals (executor, supervisor, stream_logic, registry)
- runs/internal/execution/ - execution artifacts and events handling
- runs/facade.py - high-level run facade
- runs/observer.py - run observation protocol
- runs/types.py - type definitions
- runs/store/ - simplified store interfaces (create, delete, query, event)

Refactor stream_bridge/:
- Replace old providers with contract.py and exceptions.py
- Remove async_provider.py, base.py, memory.py

Add documentation:
- README.md and README_zh.md for runtime module

Remove deprecated:
- manager.py moved to internal/
- worker.py, schemas.py
- user_context.py

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/packages/harness/deerflow/runtime/runs/internal/execution/events.py

@@ -0,0 +1,45 @@
+"""Lifecycle event helpers for run execution."""
+
+from __future__ import annotations
+
+from datetime import UTC, datetime
+from typing import Any
+
+from ...observer import LifecycleEventType, RunLifecycleEvent, RunObserver
+
+
+class RunEventEmitter:
+    """Build and dispatch lifecycle events for a single run."""
+
+    def __init__(
+        self,
+        *,
+        run_id: str,
+        thread_id: str,
+        observer: RunObserver,
+    ) -> None:
+        self._run_id = run_id
+        self._thread_id = thread_id
+        self._observer = observer
+        self._sequence = 0
+
+    @property
+    def sequence(self) -> int:
+        return self._sequence
+
+    async def emit(
+        self,
+        event_type: LifecycleEventType,
+        payload: dict[str, Any] | None = None,
+    ) -> None:
+        self._sequence += 1
+        event = RunLifecycleEvent(
+            event_id=f"{self._run_id}:{event_type.value}:{self._sequence}",
+            event_type=event_type,
+            run_id=self._run_id,
+            thread_id=self._thread_id,
+            sequence=self._sequence,
+            occurred_at=datetime.now(UTC),
+            payload=payload or {},
+        )
+        await self._observer.on_event(event)