fix(mana-auth) + chore: rewrite /api/v1/auth/login JWT mint, remove Matrix stack

This commit bundles two unrelated changes that were swept together by an
accidental `git add -A` in another working session. Documented here so the
history reflects what's actually inside.

═══════════════════════════════════════════════════════════════════════
1. fix(mana-auth): /api/v1/auth/login mints JWT via auth.handler instead
   of api.signInEmail
═══════════════════════════════════════════════════════════════════════

Previous attempt (commit 55cc75e7d) tried to fix the broken JWT mint in
/api/v1/auth/login by switching the cookie name from `mana.session_token`
to `__Secure-mana.session_token` for production. That was necessary but
not sufficient: Better Auth's session cookie value isn't just the raw
session token, it's `<token>.<HMAC>` where the HMAC is derived from the
better-auth secret. Reconstructing the cookie from auth.api.signInEmail's
JSON response only gave us the raw token, so /api/auth/token's
get-session middleware still couldn't validate it and the JWT mint kept
silently failing.

Real fix: do the sign-in via auth.handler (the HTTP path) rather than
auth.api.signInEmail (the SDK path). The handler returns a real fetch
Response with a Set-Cookie header containing the fully signed cookie
envelope. We capture that header verbatim and forward it as the cookie
on the /api/auth/token request, which now passes validation and mints
the JWT correctly.

Verified end-to-end on auth.mana.how:

  $ curl -X POST https://auth.mana.how/api/v1/auth/login \
      -d '{"email":"...","password":"..."}'
  {
    "user": {...},
    "token": "<session token>",
    "accessToken": "eyJhbGciOiJFZERTQSI...",   ← real JWT now
    "refreshToken": "<session token>"
  }

Side benefits:
- Email-not-verified path is now handled by checking
  signInResponse.status === 403 directly, no more catching APIError
  with the comment-noted async-stream footgun.
- X-Forwarded-For is forwarded explicitly so Better Auth's rate limiter
  and our security log see the real client IP.
- The leftover catch block now only handles unexpected exceptions
  (network errors etc); the FORBIDDEN-checking logic in it is dead but
  harmless and left in for defense in depth.

═══════════════════════════════════════════════════════════════════════
2. chore: remove the entire self-hosted Matrix stack (Synapse, Element,
   Manalink, mana-matrix-bot)
═══════════════════════════════════════════════════════════════════════

The Matrix subsystem ran parallel to the main Mana product without any
load-bearing integration: the unified web app never imported matrix-js-sdk,
the chat module uses mana-sync (local-first), and mana-matrix-bot's
plugins duplicated features the unified app already ships natively.
Keeping it alive cost a Synapse + Element + matrix-web + bot container
quartet, three Cloudflare routes, an OIDC provider plugin in mana-auth,
and a steady drip of devlog/dependency churn.

Removed:
- apps/matrix (Manalink web + mobile, ~150 files)
- services/mana-matrix-bot (Go bot with ~20 plugins)
- docker/matrix configs (Synapse + Element)
- synapse/element-web/matrix-web/mana-matrix-bot services in
  docker-compose.macmini.yml
- matrix.mana.how/element.mana.how/link.mana.how Cloudflare tunnel routes
- OIDC provider plugin + matrix-synapse trustedClient + matrixUserLinks
  table from mana-auth (oauth_* schema definitions also removed)
- MatrixService import path in mana-media (importFromMatrix endpoint)
- Matrix notification channel in mana-notify (worker, metrics, config,
  channel_type enum, MatrixOptions handler)
- Matrix entries from shared-branding (mana-apps + app-icons),
  notify-client, the i18n bundle, the observatory map, the credits
  app-label list, the landing footer/apps page, the prometheus + alerts
  + promtail tier mappings, and the matrix-related deploy paths in
  cd-macmini.yml + ci.yml

Devlog/manascore/blueprint entries that mention Matrix are left intact
as historical record. The oauth_* + matrix_user_links Postgres tables
stay on existing prod databases — code can no longer write to them, drop
them in a follow-up migration if you want them gone for real.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

packages/notify-client/src/client.ts

@@ -1,7 +1,6 @@
 import type {
 	SendEmailOptions,
 	SendPushOptions,
-	SendMatrixOptions,
 	SendWebhookOptions,
 	ScheduleOptions,
 	NotificationResponse,
@@ -82,24 +81,6 @@ export class NotifyClient {
 		});
 	}
 
-	/**
-	 * Send a Matrix message
-	 */
-	async sendMatrix(options: SendMatrixOptions): Promise<NotificationResponse> {
-		return this.send({
-			channel: 'matrix',
-			appId: this.appId,
-			recipient: options.roomId,
-			body: options.body,
-			matrixOptions: {
-				formattedBody: options.formattedBody,
-				msgtype: options.msgtype,
-			},
-			priority: options.priority,
-			externalId: options.externalId,
-		});
-	}
-
 	/**
 	 * Send a webhook notification
 	 */
@@ -184,7 +165,6 @@ export class NotifyClient {
 		notifications: Array<
 			| ({ type: 'email' } & SendEmailOptions)
 			| ({ type: 'push' } & SendPushOptions)
-			| ({ type: 'matrix' } & SendMatrixOptions)
 			| ({ type: 'webhook' } & SendWebhookOptions)
 		>
 	): Promise<BatchNotificationResponse> {
@@ -214,15 +194,6 @@ export class NotifyClient {
 					priority: n.priority,
 					externalId: n.externalId,
 				};
-			} else if (n.type === 'matrix') {
-				return {
-					channel: 'matrix' as const,
-					appId: this.appId,
-					recipient: n.roomId,
-					body: n.body,
-					priority: n.priority,
-					externalId: n.externalId,
-				};
 			} else {
 				return {
 					channel: 'webhook' as const,

packages/notify-client/src/types.ts

@@ -1,4 +1,4 @@
-export type NotificationChannel = 'email' | 'push' | 'matrix' | 'webhook';
+export type NotificationChannel = 'email' | 'push' | 'webhook';
 export type NotificationPriority = 'low' | 'normal' | 'high' | 'critical';
 export type NotificationStatus = 'pending' | 'processing' | 'delivered' | 'failed' | 'cancelled';
 
@@ -28,15 +28,6 @@ export interface SendPushOptions {
 	externalId?: string;
 }
 
-export interface SendMatrixOptions {
-	roomId: string;
-	body: string;
-	formattedBody?: string;
-	msgtype?: 'text' | 'notice';
-	priority?: NotificationPriority;
-	externalId?: string;
-}
-
 export interface SendWebhookOptions {
 	url: string;
 	method?: 'POST' | 'PUT';