refactor: wave 1 - extract leaf modules, rename catch-all files, split index.ts hooks

- Split 25+ index.ts files into hook.ts + extracted modules
- Rename all catch-all utils.ts/helpers.ts to domain-specific names
- Split src/tools/lsp/ into ~15 focused modules
- Split src/tools/delegate-task/ into ~18 focused modules
- Separate shared types from implementation
- 155 files changed, 60+ new files created
- All typecheck clean, 61 tests pass

src/hooks/rules-injector/cache.ts

@@ -0,0 +1,27 @@
+import { clearInjectedRules, loadInjectedRules } from "./storage";
+
+export type SessionInjectedRulesCache = {
+  contentHashes: Set<string>;
+  realPaths: Set<string>;
+};
+
+export function createSessionCacheStore(): {
+  getSessionCache: (sessionID: string) => SessionInjectedRulesCache;
+  clearSessionCache: (sessionID: string) => void;
+} {
+  const sessionCaches = new Map<string, SessionInjectedRulesCache>();
+
+  function getSessionCache(sessionID: string): SessionInjectedRulesCache {
+    if (!sessionCaches.has(sessionID)) {
+      sessionCaches.set(sessionID, loadInjectedRules(sessionID));
+    }
+    return sessionCaches.get(sessionID)!;
+  }
+
+  function clearSessionCache(sessionID: string): void {
+    sessionCaches.delete(sessionID);
+    clearInjectedRules(sessionID);
+  }
+
+  return { getSessionCache, clearSessionCache };
+}