feat(mnote-web): replace SSE pollMs=1000 polling with WebSocket push for tree realtime events

## Problem
Convex backend RSS grew to 7.7G due to ~17 HTTP POST /api/query/min
(32K+ in 32h) from the SSE polling loop in /api/tree/events?pollMs=1000.
Each poll triggered a Convex query even when nothing changed.

## Root Cause
The tree live EventSource client polled every 1s via SSE, calling
load_stream_overview() → execute_runtime_query_via_convex() → Convex
POST /api/query on every cycle, regardless of workspace state.

## Solution
Replace polling with push: add a `stream_delta_tx` broadcast channel
that publishes after every Convex mutation, consumed by WebSocket and
SSE endpoints for push-only delivery.

### Server-side
- **app.rs**: Add `stream_delta_tx: broadcast::Sender<Value>` to AppState
- **command_support.rs**: `execute_runtime_command_via_convex_with_artifacts`
  now takes `&AppState` (was `&AppConfig`) and pushes `{"kind":"command_committed",...}`
  to `stream_delta_tx` after every successful mutation
- **ws.rs**: Rewrite `handle_socket` with `tokio::select!` subscribing to
  `stream_delta_tx`; pushes delta events to WS clients on mutation, handles
  client `resync` requests for fresh snapshots
- **sse.rs**: `tree_events` endpoint now subscribes to both `block_delta_tx`
  and `stream_delta_tx`; when broadcast channels are available, runs in
  push-only mode (250ms heartbeat, no Convex query). Polling degrades to
  60s safety net. Keeps backward compatibility for non-WS clients.

### Client-side
- **layout.rs**: Bootstrap JSON now defaults to `transport: "convex-command-log-ws"`
  with `wsEndpoint: "/api/realtime/ws"`. TREE_LIVE_CONTROLLER_JS extended
  with `startWithWebSocket()` supporting snapshot/delta/resync/lagged-hint
  events; auto-fallback to SSE on WS failure after 2s.

### Caller updates (17 call sites)
- documents.rs, mindmap_api.rs, resource_trash.rs, tree.rs
- hermes_tools/{artifact,block,page}.rs
All updated from `state.config()` to `&state` for the new signature.

## Verification
- `cargo build` + `cargo test`: 295/298 passed (3 pre-existing failures)
- Browser smoke: page loaded → transport=convex-command-log-ws, status=connected
- Convex logs: 0 POST /api/query in 2min with page idle (vs ~17/min before)
- Initial burst: 8 queries on page load (normal), then silence

rust/crates/mnote-web/src/hermes_tools/manifest.rs

@@ -22,6 +22,7 @@ pub fn manifest() -> Value {
             block_delete_tool(),
             block_move_after_tool(),
             doc_apply_block_ops_tool(),
+            doc_markdown_edit_tool(),
             page_get_tool(),
             page_save_tool(),
             available_tool("mnote.page.update_title", "更新当前页面标题", ["page.write"]),
@@ -409,6 +410,43 @@ fn available_tool(
     })
 }
 
+fn doc_markdown_edit_tool() -> Value {
+    let mut properties = base_identity_properties();
+    if let Value::Object(map) = &mut properties {
+        map.insert(
+            "operations".into(),
+            json!({
+                "type": "array",
+                "description": "搜索替换操作列表",
+                "items": {
+                    "type": "object",
+                    "properties": {
+                        "search": { "type": "string", "description": "要搜索的原文片段" },
+                        "replace": { "type": "string", "description": "替换后的新文本" }
+                    },
+                    "required": ["search", "replace"]
+                }
+            }),
+        );
+        map.insert(
+            "full_content".into(),
+            json!({
+                "type": "string",
+                "description": "完整修改后的 markdown 文本（替代 operations）"
+            }),
+        );
+    }
+    json!({
+        "name": "mnote.doc.markdown_edit",
+        "description": "通过文本级搜索替换编辑 markdown 内容（AI 编辑主路径）。在线 Convex 文档和本地 .md 文件共用，不需要 blockId。",
+        "schemaVersion": TOOL_SCHEMA_VERSION,
+        "capabilityScope": ["block.write", "page.write"],
+        "status": "available",
+        "properties": properties,
+        "annotations": tool_annotations(false, false, true, false)
+    })
+}
+
 fn tool_annotations(
     readonly: bool,
     destructive: bool,