refactor: rename Fabled Assistant to Fabled Scribe

Updates user-visible branding across frontend (PWA manifest, page title,
Settings, push fallback), backend (email templates and subjects, LLM
system prompt, CalDAV displayname, SMTP from-name default), README,
quickstart compose, and MCP server description.

Also updates the CI image path and quickstart image reference to
git.fabledsword.com/bvandeusen/fabledscribe in preparation for the
Forgejo repo rename. Internal Python package, env vars, and database
schema unchanged.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/fabledassistant/config.py

@@ -52,7 +52,7 @@ class Config:
     SMTP_USERNAME: str = os.environ.get("SMTP_USERNAME", "")
     SMTP_PASSWORD: str = _read_secret("SMTP_PASSWORD", "SMTP_PASSWORD_FILE", "")
     SMTP_FROM_ADDRESS: str = os.environ.get("SMTP_FROM_ADDRESS", "")
-    SMTP_FROM_NAME: str = os.environ.get("SMTP_FROM_NAME", "Fabled Assistant")
+    SMTP_FROM_NAME: str = os.environ.get("SMTP_FROM_NAME", "Fabled Scribe")
     SMTP_USE_TLS: bool = os.environ.get("SMTP_USE_TLS", "true").lower() in ("1", "true", "yes")
     BASE_URL: str = os.environ.get("BASE_URL", "http://localhost:5000").rstrip("/")
     TRUST_PROXY_HEADERS: bool = os.environ.get("TRUST_PROXY_HEADERS", "").lower() in ("1", "true", "yes")