feat(server): add institutional memory recall

- File-based memory under .boocode/memory/ (project/user/reference topics)
- Hierarchical 4-scope scan: global → home → project → session
- Keyword/tag relevance matching for query-based recall
- Injected as <boocode-memory> block in system prompt at assembly
- v1 recall-only (extract/dream deferred to v2)

apps/server/src/services/memory/store.ts

@@ -0,0 +1,35 @@
+import { readFile, writeFile, readdir } from 'node:fs/promises';
+import { join } from 'node:path';
+import type { MemoryTopic } from './paths.js';
+import { getTopicDir } from './paths.js';
+
+export async function readTopicFiles(root: string, topic: MemoryTopic): Promise<Map<string, string>> {
+  const dir = getTopicDir(root, topic);
+  const files = new Map<string, string>();
+  try {
+    const entries = await readdir(dir, { withFileTypes: true });
+    for (const entry of entries) {
+      if (entry.isFile() && entry.name.endsWith('.md')) {
+        const content = await readFile(join(dir, entry.name), 'utf8');
+        files.set(entry.name, content);
+      }
+    }
+  } catch {
+    // Directory doesn't exist yet
+  }
+  return files;
+}
+
+export async function writeEntry(
+  root: string,
+  topic: MemoryTopic,
+  title: string,
+  content: string,
+  tags: string[],
+): Promise<void> {
+  const dir = getTopicDir(root, topic);
+  const tagLine = tags.length > 0 ? `> tags: ${tags.join(', ')}\n\n` : '\n';
+  const entry = `## ${topic}: ${title}\n${tagLine}${content}\n`;
+  const filename = title.toLowerCase().replace(/[^a-z0-9]+/g, '-').replace(/(^-|-$)/g, '') + '.md';
+  await writeFile(join(dir, filename), entry, 'utf8');
+}