Add #rss command family with LLM tags and summaries (v0.20.0)

#rss subcommands on the command channel: help / add <url> <name> /
remove <name> / tags / sources / get <name|#tag>. Sources are stored in
a new rss_sources table in the existing MESH_DB_PATH file (second
node:sqlite connection, case-insensitive names); feeds parsed with
fast-xml-parser (RSS 2.0 + Atom); AI tags and headline summaries via
injected LlmService.chat() with bounded maxTokens (50/200).

CommandService gains prefix registration so one handler owns the whole
#rss family while #ping stays an exact match; wired in CommandModule's
factory — still no constructor-level cycle, no forwardRef. One dead feed
does not sink a tag summary.

src/rss/rss.store.spec.ts

@@ -0,0 +1,80 @@
+import { mkdtempSync, rmSync } from 'node:fs';
+import { tmpdir } from 'node:os';
+import { join } from 'node:path';
+import { DatabaseSync } from 'node:sqlite';
+import { afterEach, beforeEach, describe, expect, it } from 'vitest';
+import { RssStore } from './rss.store.js';
+
+describe('RssStore (real SQLite file)', () => {
+  let dir: string;
+  let store: RssStore;
+
+  beforeEach(() => {
+    dir = mkdtempSync(join(tmpdir(), 'mesh-bot-rss-'));
+    const db = new DatabaseSync(join(dir, 'test.db'));
+    store = new RssStore(db);
+  });
+
+  afterEach(() => {
+    rmSync(dir, { recursive: true, force: true });
+  });
+
+  it('adds and lists sources with tags round-tripped through the comma string', () => {
+    store.add({
+      name: 'Hacker News',
+      url: 'https://news.ycombinator.com/rss',
+      tags: ['tech', 'news'],
+    });
+    store.add({ name: 'LWN', url: 'https://lwn.net/headlines.rss', tags: [] });
+
+    expect(store.list()).toEqual([
+      {
+        name: 'Hacker News',
+        url: 'https://news.ycombinator.com/rss',
+        tags: ['tech', 'news'],
+        createdAt: expect.any(Number),
+      },
+      {
+        name: 'LWN',
+        url: 'https://lwn.net/headlines.rss',
+        tags: [],
+        createdAt: expect.any(Number),
+      },
+    ]);
+  });
+
+  it('looks up and checks existence case-insensitively', () => {
+    store.add({ name: 'My Feed', url: 'https://example.com/rss', tags: ['a'] });
+    expect(store.get('my feed')?.url).toBe('https://example.com/rss');
+    expect(store.get('MY FEED')).toBeDefined();
+    expect(store.exists('mY fEeD')).toBe(true);
+    expect(store.exists('other')).toBe(false);
+  });
+
+  it('removes case-insensitively and reports whether a row went', () => {
+    store.add({ name: 'Gone', url: 'https://example.com/gone', tags: [] });
+    expect(store.remove('gone')).toBe(true);
+    expect(store.list()).toEqual([]);
+    expect(store.remove('gone')).toBe(false);
+  });
+
+  it('collects all distinct tags across sources, sorted', () => {
+    store.add({
+      name: 'A',
+      url: 'https://a.example/rss',
+      tags: ['zeta', 'alpha'],
+    });
+    store.add({
+      name: 'B',
+      url: 'https://b.example/rss',
+      tags: ['beta', 'alpha'],
+    });
+    expect(store.allTags()).toEqual(['alpha', 'beta', 'zeta']);
+  });
+
+  it('persists across a second connection to the same file (the production shape)', () => {
+    store.add({ name: 'Durable', url: 'https://d.example/rss', tags: ['x'] });
+    const db2 = new DatabaseSync(join(dir, 'test.db'));
+    expect(new RssStore(db2).get('durable')?.tags).toEqual(['x']);
+  });
+});