feat: SMTP email support for invite links + profile.json for user email storage

- email_utils.py: send_email() via smtplib.SMTP_SSL (port 465, same server
  as AE API); send_invite_email() renders plain-text + HTML invite template
- config.py: smtp_server, smtp_port, smtp_username, smtp_password,
  smtp_from_email, smtp_from_name, cortex_base_url settings
- manage_passwords.py:
  - profile.json helpers (get/set email stored in home/{username}/profile.json)
  - invite command now accepts optional email arg, sends invite automatically;
    falls back to stored email; prints link either way
  - new 'email' command to store/update a user's email address
  - 'list' command now shows email alongside password status
- .env.default: SMTP_* and CORTEX_BASE_URL documented

Usage after adding SMTP_PASSWORD to .env:
  python manage_passwords.py invite holly holly@example.com
  → generates token, stores email, sends invite, prints link as fallback

All 80 tests pass.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

cortex/config.py

@@ -72,6 +72,16 @@ class Settings(BaseSettings):
     jwt_secret: str = "change-me-in-dotenv"   # override in .env: JWT_SECRET=<random>
     jwt_expire_days: int = 30
 
+    # SMTP — for sending invite emails
+    smtp_server: str = ""
+    smtp_port: int = 465
+    smtp_username: str = ""
+    smtp_password: str = ""
+    smtp_from_email: str = "noreply@oneskyit.com"
+    smtp_from_name: str = "Cortex"
+    # Base URL used in invite links (no trailing slash)
+    cortex_base_url: str = "https://cortex.dgrzone.com"
+
     host: str = "0.0.0.0"
     port: int = 8000