brand: rename product to "Read the Markets" (read.markets)

The product is now "Read the Markets" served at https://read.markets,
with the app at https://app.read.markets. "Cassandra" survives only as
the in-product AI persona (system prompt + "Ask Cassandra" chat label).

Centralised the brand in app/branding.py: BRAND_NAME, BRAND_SHORT,
DOMAIN, SITE_URL, APP_URL, EMAIL_FROM_DEFAULT. Jinja templates pull
{{ BRAND_NAME }} via globals registered in templates_env.py; Python
code reads branding.BRAND_NAME directly. The future-rename surface
is now a one-liner.

Updated: FastAPI app title, every page title (dashboard, news, log,
settings, upload, login, verify), header brand div, auth-card brands,
OTP email subject + HTML + plain-text bodies (incl. uppercase header
tag), OpenRouter X-Title + HTTP-Referer attribution headers, README.
Email tests now assert against branding.BRAND_NAME rather than the
literal string.

Internal identifiers deliberately kept on the legacy "cassandra" name
to avoid invalidating live sessions / advisory locks / configs:
cookies (cassandra_session, cassandra_pending) + itsdangerous salts,
MariaDB GET_LOCK keys, CASSANDRA_TOKEN env var, cassandra.css filename,
pyproject package name, localStorage prefs, outbound User-Agent strings.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

app/services/openrouter.py

@@ -13,6 +13,7 @@ from datetime import datetime, timedelta, timezone
 import httpx
 from tenacity import retry, retry_if_exception_type, stop_after_attempt, wait_exponential
 
+from app import branding
 from app.config import get_settings
 
 
@@ -521,9 +522,10 @@ def _endpoint_for(provider: str) -> tuple[str, str, str, dict[str, str]]:
             s.OPENROUTER_API_KEY,
             s.OPENROUTER_MODEL,
             {
-                # OpenRouter-specific attribution headers.
-                "HTTP-Referer": "https://github.com/local/cassandra",
-                "X-Title": "Cassandra",
+                # OpenRouter-specific attribution headers. Visible on the
+                # OpenRouter dashboard — keep aligned with the live brand.
+                "HTTP-Referer": branding.SITE_URL,
+                "X-Title": branding.BRAND_NAME,
             },
         )
     raise RuntimeError(f"Unknown LLM provider: {provider!r}")