feat: add evidence search and stabilize pdf previews

- add document evidence parsing/search/open routes, Hermes tool wiring, local index settings/status, and the document-evidence skill plus design notes
- fix PDF resource tabs by rendering PDFs inline with pdf.js canvases instead of iframe preview pages, release PDF documents on close, and document the fourth-PDF stall bug
- keep PDF preview at 2x rendering while removing the previous lazy-load/placeholder direction, and make dev:hot bind loopback defaults externally reachable

Verification:
- node --check rust/crates/mnote-web/browser/document-resource-tab-runtime.js
- node scripts/task-dev-hot-plan-test.js
- cargo test -p mnote-web --manifest-path rust/Cargo.toml pdf_preview_page_does_not_render_visible_toolbar
- cargo test -p mnote-web --manifest-path rust/Cargo.toml document_shell_returns_page_aggregate_snapshot
- cargo build -p mnote-web --manifest-path rust/Cargo.toml
- browser smoke: sequentially opened the four tea_seed_oil_cosmetic PDFs; fourth PDF rendered 15/15 canvases, iframeCount=0, browser errors=0

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

@@ -19,6 +19,9 @@ pub fn manifest() -> Value {
             context_resolve_target_tool(),
             doc_fetch_tool(),
             doc_find_tool(),
+            evidence_search_tool(),
+            evidence_read_tool(),
+            evidence_open_tool(),
             block_fetch_tool(),
             doc_plan_update_tool(),
             block_replace_tool(),
@@ -249,6 +252,104 @@ fn doc_find_tool() -> Value {
     })
 }
 
+fn evidence_search_tool() -> Value {
+    let mut properties = base_identity_properties();
+    if let Value::Object(map) = &mut properties {
+        map.insert("query".into(), json!({ "type": "string" }));
+        map.insert("rootUri".into(), json!({ "type": "string" }));
+        map.insert(
+            "includeResources".into(),
+            json!({ "type": "boolean", "default": true }),
+        );
+        map.insert(
+            "includeOcr".into(),
+            json!({ "type": "boolean", "default": true }),
+        );
+        map.insert(
+            "mode".into(),
+            json!({ "type": "string", "enum": ["keyword", "tree", "hybrid", "graph"], "default": "hybrid" }),
+        );
+        map.insert("topK".into(), json!({ "type": "integer", "default": 8 }));
+        map.insert(
+            "scope".into(),
+            json!({
+                "type": "object",
+                "properties": {
+                    "workspaceId": { "type": "string" },
+                    "rootUri": { "type": "string" },
+                    "targetDocumentId": { "type": "string" },
+                    "includeResources": { "type": "boolean" },
+                    "includeOcr": { "type": "boolean" }
+                }
+            }),
+        );
+    }
+    json!({
+        "name": "mnote.evidence.search",
+        "description": "搜索可回跳原文的文档证据，返回 quote、EvidenceLocator 与 openAction。",
+        "schemaVersion": TOOL_SCHEMA_VERSION,
+        "capabilityScope": ["evidence.read", "page.read"],
+        "status": "available",
+        "annotations": tool_annotations(true, false, true, false),
+        "inputSchema": {
+            "type": "object",
+            "required": ["workspaceId", "rootUri", "query"],
+            "properties": properties
+        }
+    })
+}
+
+fn evidence_read_tool() -> Value {
+    let mut properties = base_identity_properties();
+    if let Value::Object(map) = &mut properties {
+        map.insert("locator".into(), json!({ "type": "object" }));
+        map.insert(
+            "context".into(),
+            json!({
+                "type": "object",
+                "properties": {
+                    "beforeBlocks": { "type": "integer", "default": 3 },
+                    "afterBlocks": { "type": "integer", "default": 3 },
+                    "includeSectionSummary": { "type": "boolean", "default": true }
+                }
+            }),
+        );
+    }
+    json!({
+        "name": "mnote.evidence.read",
+        "description": "按 EvidenceLocator 读取原文证据及周边上下文，供回答引用。",
+        "schemaVersion": TOOL_SCHEMA_VERSION,
+        "capabilityScope": ["evidence.read", "page.read"],
+        "status": "available",
+        "annotations": tool_annotations(true, false, true, false),
+        "inputSchema": {
+            "type": "object",
+            "required": ["locator"],
+            "properties": properties
+        }
+    })
+}
+
+fn evidence_open_tool() -> Value {
+    let mut properties = base_identity_properties();
+    if let Value::Object(map) = &mut properties {
+        map.insert("locator".into(), json!({ "type": "object" }));
+    }
+    json!({
+        "name": "mnote.evidence.open",
+        "description": "把 EvidenceLocator 归一化为 MNote 可执行的打开/定位动作。",
+        "schemaVersion": TOOL_SCHEMA_VERSION,
+        "capabilityScope": ["evidence.read", "page.read"],
+        "status": "available",
+        "annotations": tool_annotations(true, false, true, false),
+        "inputSchema": {
+            "type": "object",
+            "required": ["locator"],
+            "properties": properties
+        }
+    })
+}
+
 fn block_fetch_tool() -> Value {
     let mut properties = base_identity_properties();
     if let Value::Object(map) = &mut properties {