Rebrand, SEO infrastructure, legal pages, landing polish

[feature] Rebrand to Manage Agency — New name, new Nanobanana-inspired M/A monogram, new domain at manageagency.app, and brand colour #7C3AED throughout.

[feature] Legal pages live — /privacy, /terms, and /contact with a shared branded layout, sitemap entries, and unauthenticated access.

[feature] Landing FAQ + trust row + roadmap — Eight FAQs with FAQPage schema, a tech-stack trust row, and a two-column roadmap section.

[feature] Integrations catalogue — /settings/integrations with 8 planned connectors (Gmail, Google Calendar, GA4, Stripe, Slack, Vercel, DocuSign, Zapier).

[feature] Keyboard shortcuts cheat sheet — Press ? anywhere in the signed-in app to open the shortcuts modal.

[feature] Mobile-responsive sidebars — Agency + client sidebars collapse to a slide-in drawer with a hamburger in the header below the lg breakpoint.

[infra] SEO infrastructure — robots.txt, sitemap.xml, /.well-known/security.txt, manifest.webmanifest, and JSON-LD graph (Organization, WebSite, SoftwareApplication, FAQPage).

[infra] Vercel Analytics + Speed Insights — Live traffic and Core Web Vitals reporting on manageagency.app.

[infra] Next.js error / loading / 404 UI — Branded not-found, error, global-error, and per-group loading skeletons.

[security] Fix middleware blocking SEO routes — robots.txt, sitemap.xml, and /.well-known/security.txt were being 307'd to sign-in. Crawlers and security researchers now reach them unauthenticated.