Separate the gateway demo from the Community Directory

[randomblocker]

Summary

• Removes the gateway-specific /try and /try-chat applications, Butler contracts/forms, environment variables, probes, and demo tests from the Community Directory.
• Refocuses the homepage and navigation on chain-indexed service discovery, evidence inspection, registration, and the machine-readable catalog.
• Replaces the demo-origin deployment check with a strict validation of the Directory's own canonical HTTPS origin.
• Keeps the generic indexer, catalog APIs, signed publication flow, Demos discovery/wallet support, endpoint safety, x402 metadata, verification, and Counterparty Evidence service unchanged.

Why

The Community application owns public indexing and discovery. The gateway owns its custodied buyer demo. The Directory should not depend on, select for, or embed one demo gateway.

Impact and rollout

This PR remains a draft until the gateway-owned UI in dacs-agents PR #11 has been built, deployed, and smoke-tested.

Because browser recovery state is origin-scoped, this removal cannot be the first drain step. A separate recovery-only Directory release (or equivalent reviewed control) must first stop new purchases while preserving the old page, with the exact Directory HTTPS origin temporarily retained in the gateway's CORS allowlist. After at least the documented 12-minute recovery window and reconciliation of outstanding jobs, this removal can deploy and the temporary CORS entry can be removed.

There is deliberately no redirect or runtime gateway dependency in Community.

Validation

• Unit/integration tests: 150/150
• Production typecheck and build: pass
• Playwright desktop/mobile coverage: 6/6
• Directory-origin contract tests: 2/2
• Final diff checks: pass