feat(rag): harden post-LightRAG runtime

Retire legacy OCR/media/evidence fallbacks, add local-folder event bus and Page Aggregate guards, and archive completed design checklists.

Validation: cargo test -p mnote-web -- --test-threads=1; cargo test --workspace -- --test-threads=1; git diff --check; codegraph sync .; codegraph_status.

rust/crates/mnote-web/src/app.rs

@@ -9,10 +9,9 @@ use axum::middleware::Next;
 use axum::response::Response;
 use axum::Router;
 use control_plane::{ControlPlaneStore, SqliteControlPlaneStore};
-use std::collections::BTreeMap;
 use std::env;
 use std::fs;
-use std::sync::{Arc, RwLock};
+use std::sync::Arc;
 use tower_http::trace::TraceLayer;
 use tracing::{error, warn};
 
@@ -140,8 +139,6 @@ pub struct AppState {
     pub editor_actor: EditorRuntimeActor,
     pub block_delta_tx: broadcast::Sender<serde_json::Value>,
     pub stream_delta_tx: broadcast::Sender<serde_json::Value>,
-    pub local_ocr_job_tx: broadcast::Sender<serde_json::Value>,
-    pub local_ocr_active_jobs: Arc<RwLock<BTreeMap<String, serde_json::Value>>>,
     pub acp_runtime: Arc<AcpRuntimeManager>,
     pub buffer_store: BufferStore,
     control_plane: Arc<SqliteControlPlaneStore>,
@@ -151,7 +148,6 @@ impl AppState {
     pub fn new(config: AppConfig) -> Self {
         let (block_delta_tx, _) = broadcast::channel(256);
         let (stream_delta_tx, _) = broadcast::channel(256);
-        let (local_ocr_job_tx, _) = broadcast::channel(256);
         let actor = EditorRuntimeActor::new();
         actor.set_block_delta_tx(block_delta_tx.clone());
         let buffer_store = BufferStore::new();
@@ -165,8 +161,6 @@ impl AppState {
             editor_actor: actor,
             block_delta_tx,
             stream_delta_tx,
-            local_ocr_job_tx,
-            local_ocr_active_jobs: Arc::new(RwLock::new(BTreeMap::new())),
             acp_runtime: Arc::new(AcpRuntimeManager::from_env()),
             buffer_store,
             control_plane,