feat(engine): Baileys engine — minimal slice (link + text send/receive)

[rmyndharis]

Summary

Adds a second, browser-free WhatsApp engine to OpenWA: @whiskeysockets/baileys (WebSocket/Noise protocol, no Chromium). This is slice 1 of a decomposed effort — a minimal working engine that links a session and sends/receives text through the unchanged engine-neutral pipeline. Everything outside that minimal set is honestly capability-gated to HTTP 501.

Selectable via ENGINE_TYPE=baileys. The whatsapp-web.js engine and the default ENGINE_TYPE are untouched (backward compatible), and the work builds directly on the opaque per-engine-config foundation (#296): the factory passes only neutral fields + an opaque context.config blob each engine reads its own namespace from.

In scope (the minimal working engine)

• Lifecycle: initialize / disconnect / logout / destroy
• Auth: useMultiFileAuthState (per-session dir under BAILEYS_AUTH_DIR), QR via connection.update.qr, requestPairingCode, creds persisted on every creds.update
• Connection mapping → neutral callbacks: qr→onQRCode/QR_READY, open→onReady+phone/pushName/READY, close→ terminal on loggedOut (no reconnect) vs. auto-reconnect on recoverable closes (Baileys emits restartRequired right after pairing — reconnect is required for linking to complete), guarded against reconnecting after an intentional close
• Send text: sendTextMessage → sock.sendMessage(jid, { text })
• Recipient resolution: checkNumberExists / getNumberId via sock.onWhatsApp (powers send-to-number + the dashboard MessageTester)
• Typing presence: sendChatState → sock.sendPresenceUpdate (so the default-on anti-ban typing path works)
• Inbound: messages.upsert → onMessage (incoming) / onMessageCreate (fromMe), messages.update → onMessageAck, all mapped to the neutral IncomingMessage / DeliveryStatus by a new baileys-message-mapper (the sole Baileys-scheme→neutral boundary)

Out of scope → gated to HTTP 501

Media/location/contact/sticker sends, reply/forward/react/delete, contacts/groups/chats/history/seen, labels/catalog/channels/status — every one throws the new typed EngineNotSupportedError (→ 501). No self-maintained store in this slice (that's the largest piece of net-new infra; it unlocks most of the above in later slices). getFeatures() advertises only ['text-messages', 'typing-indicator'].

⚠️ Breaking: Node.js ≥ 20.19 now required

@whiskeysockets/baileys is ESM-only ("type": "module"). OpenWA is CommonJS, so it require()s the lib at startup, and because the engine factory statically imports the Baileys plugin, the lib loads on every boot — even with the default whatsapp-web.js engine. require()-of-ESM needs Node ≥ 20.19 (and 22.12+); on older Node the app would fail to boot with ERR_REQUIRE_ESM. This PR declares engines.node >= 20.19.0 and documents it (CI + Docker already run Node 22). Operators on EOL Node 18 must upgrade. → targets v0.3.0 per the SemVer policy.

Alternative considered: lazy-import() the Baileys lib so wwjs-only users keep Node 18. Deferred in favor of declaring the floor (Node 18 is EOL since April 2025). Happy to switch to the lazy-load approach if you'd prefer to preserve the older floor — say the word before merge.

Notes

• Dependency pinned exactly to @whiskeysockets/baileys@6.7.23 (stable 6.x), not npm's latest (7.0.0-rc13, a pre-release). Core APIs are unchanged across 6→7; the adapter + baileys.types.ts boundary isolates a future bump.
• Proxy is gated on this engine for slice 1 (Baileys proxying needs an http/socks agent dependency); a configured proxyUrl is logged-and-ignored and documented in .env.example.
• Baileys' own JID schemes (@s.whatsapp.net / @g.us / @lid / status@broadcast) and proto types stay strictly inside the adapter + mapper + types files — nothing leaks into the neutral pipeline, webhooks, or dashboard.

Testing

• 566 unit tests + 6 e2e green; backend lint 0 / build clean; dashboard build clean / lint 0 errors.
• New coverage: baileys-message-mapper (neutral shaping, @lid/group/fromMe/status), the adapter (QR/open/close + reconnect-vs-terminal, gating, text send, recipient resolution, presence, inbound fan-out, pairing-code guard), the plugin (opaque-config read + fallback + minimal feature set), and a factory-registration test.
• E2E boot gate (test/baileys-engine.e2e-spec.ts): boots the full AppModule with ENGINE_TYPE=baileys and asserts the engine is selected + the plugin enabled — without connecting a socket. (This is also the gate that catches DI module-load cycles.)
• The CommonJS app's runtime require() of the ESM lib was verified directly on Node 22 (all symbols resolve); the jest stub for Baileys is a test-environment workaround only (ts-jest can't load type: module), not a masked runtime break.

Next slices

• Slice 2: media/location/contact/sticker sends + reply/forward/react/delete (introduces the message store)
• Slice 3: contacts + groups + chats/history/seen (store-backed)