fix(proxy): make /docs public so the docs site is reachable without a session

The new /docs section is static, public help content, but proxy.ts (the auth
middleware) redirects any non-allowlisted path to /login, so unauthenticated
visitors were bounced off /docs to the login page. Add /docs to PUBLIC_ROUTES
(covers /docs and every /docs/<category>/<slug>); screenshots under /docs-media
already bypass the middleware via the image matcher.

Verified locally with no session: /docs and doc pages return 200, while
/dashboard and /members still redirect to /login.

proxy.ts

@@ -47,6 +47,11 @@ const PUBLIC_ROUTES = [
   // submitForm enforces visibility). The /forms* management routes do NOT
   // match the '/f/' prefix and stay auth-gated.
   '/f',
+  // Public documentation site. /docs and every /docs/<category>/<slug> page are
+  // static, read-only marketing/help content and must be reachable anonymously
+  // (they render no member data). Screenshots under /docs-media/* are static
+  // image files and already bypass the middleware via the matcher below.
+  '/docs',
   '/resources',
   '/zine',
   '/governance',