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:
- The 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.

docs/URL_SCHEMA.md

@@ -39,15 +39,12 @@ This document defines the URL schema for all mana.how subdomains.
 | **Media Service** | media.mana.how | Image/video processing |
 | **LLM Service** | llm.mana.how | LLM abstraction layer |
 | **LLM Playground** | playground.mana.how | LLM testing interface |
-| **Link Shortener** | link.mana.how | URL shortener (uload) |
 | **File Storage** | files.mana.how | MinIO/S3 file access |
 
-### Matrix/Communication
+### Automation
 
 | Service | URL | Description |
 |---------|-----|-------------|
-| **Matrix Server** | matrix.mana.how | Synapse homeserver |
-| **Element Web** | element.mana.how | Matrix web client |
 | **N8N** | n.mana.how | Workflow automation |
 
 ### Monitoring & Admin