feat(engine): Baileys group management + profile + block/unblock (slice 3a)

[rmyndharis]

Summary

Slice 3a of the Baileys engine: un-gates the storeless live ops — all group management, profile-picture fetch, and block/unblock — via direct Baileys socket calls. No store, no DB, no DI changes.

Stacked on #308 (base branch feat/baileys-store-ops, itself stacked on #307 → #299). This PR's diff is slice-3a only; the base retargets to main as the stack merges down.

What's added (15 methods, all ensureReady()-guarded)

• Group management: getGroups (groupFetchAllParticipating, one call — no N+1), getGroupInfo (groupMetadata), createGroup, participant ops (groupParticipantsUpdate with add/remove/promote/demote), leaveGroup, setGroupSubject/setGroupDescription, getGroupInviteCode/revokeGroupInviteCode.
• getProfilePicture (profilePictureUrl → url, or null when none/hidden).
• blockContact/unblockContact (updateBlockStatus).
• New pure baileys-group-mapper (GroupMetadata → neutral Group/GroupInfo/GroupParticipant) — the sole Baileys-group→neutral boundary (type-only baileys import, no runtime load, unit-tested without a socket). Group.isAdmin is computed by matching the session's own JID against admin/superadmin participants.
• getFeatures() now advertises group-management.

Behavior notes

• getGroupInfo / getProfilePicture degrade to null on rejection (no such group / no picture / hidden), with a debug log for operator traceability — matching the neutral | null contract.
• isAnnounce/isReadOnly are mapped best-effort from Baileys' announce flag (WhatsApp's announce/restrict semantics are fuzzy).

Out of scope (still 501)

getContacts/getContactById/getChats/sendSeen/getChatHistory/deleteChat/resolveContactPhone → the contact/chat-store slice (3b). Labels/channels/status/catalog/getMessageReactions stay unsupported (parity with the whatsapp-web.js engine, which also stubs them).

Testing

• 613 unit + 6 e2e green; backend lint 0 / build clean; dashboard build clean / lint 0 errors.
• New coverage: group mapper (mapped shapes, self-admin true/false/superadmin/plain-admin, linked parent); adapter (each op → exact sock.* call + args, getGroups/getGroupInfo mapped, getGroupInfo null-on-reject, invite codes, profile url + null, block/unblock action literals, ensureReady pre-connect); the e2e boot-gate feature list synced to the 10-entry set.