Promote AgentCompany-New to the repository root and retire the old app

The legacy application - its src, tests, landing site, promo assets, docs,
release tooling, CI workflows, and root configs - leaves the tree; it stays
reachable in history. Everything under AgentCompany-New moves up unchanged:
same package name, so the production userData/database path is untouched,
and e2e/build scripts already resolved paths relative to the project. The
developer cred.txt stays gitignored at its new location. Full verify:ci
passes from the new root.

landing/_headers

@@ -1,21 +0,0 @@
-/*
-  Content-Security-Policy: default-src 'self'; script-src 'self' 'unsafe-inline' https://static.cloudflareinsights.com; style-src 'self' 'unsafe-inline' https://fonts.googleapis.com; font-src 'self' https://fonts.gstatic.com data:; img-src 'self' data:; connect-src 'self' https://cloudflareinsights.com; base-uri 'self'; form-action 'self'; frame-ancestors 'none'
-  Permissions-Policy: camera=(), microphone=(), geolocation=()
-  Referrer-Policy: strict-origin-when-cross-origin
-  X-Content-Type-Options: nosniff
-  X-Frame-Options: DENY
-
-/screenshots/*
-  Cache-Control: public, max-age=31536000, immutable
-
-/assets/*
-  Cache-Control: public, max-age=31536000, immutable
-
-/_next/static/*
-  Cache-Control: public, max-age=31536000, immutable
-
-/favicon.ico
-  Cache-Control: public, max-age=31536000, immutable
-
-/icon.png
-  Cache-Control: public, max-age=31536000, immutable