feat: prepare RatelDesk API, MCP, and release tooling

[Proxicon]

Closes #61

Delivered

• Caller-bound local HTTP MCP gateway pairing and delegation: opaque rdk_ MCP credentials are purpose- and resource-bound, exchanged only for short-lived request-scoped API execution credentials, and never forwarded to business APIs. Explicit authentik mode remains available separately.
• Credential lifecycle and account management: interactive management-session policy, CSRF-protected account UI, one-time secret reveal, expiry/revocation, organization-and-permission tuples, current membership/RBAC evaluation, SQLite-safe chronological ordering, and forward identity migrations.
• OpenAPI and Scalar: deterministic Release-mode catalog/taxonomy, accurate anonymous/local-cookie/opaque-credential/machine security descriptions, product version, Web-proxy Try It route, and a rendered Scalar browser check with an attached screenshot artifact.
• Compose and release readiness: validated local/Authentik MCP examples with an origin allowlist and non-root config handoff; exact validated release payload transfer, draft-only upload/completeness/conflict safeguards, and extracted archive execution on Linux and Windows matching runners.
• CLI/stdio: integration-credential identity diagnostics, caller-derived assignment identity, and cache partitioning without secret-bearing cache keys.

Supported executable archives

Releases deliberately support only Linux x64, Linux ARM64, and Windows x64 for self-contained rateldesk CLI and rateldesk-mcp stdio archives. macOS archives and macOS runner jobs were retired at 1430eb1; they are not packaged, checksummed, uploaded, or advertised as supported artifacts. The payload expectation is enforced in package, manifest, upload, and extracted-archive validation scripts.

Requirement-to-test mapping

Review area	Primary automated coverage
A1, A7: local/external MCP, delegation, purpose separation, concurrency, CLI/stdio	McpGatewayDelegationEndpointTests, McpHttpHostTests, HelpdeskToolsMutationTests, HelpdeskCliTests
A2, B3: payload transfer, draft upload safety, archive execution	tools/release/test-publish-release-assets.sh, tools/release/test-executable-archives.sh, release rehearsal and Linux/Windows archive-runtime CI jobs
A3, A4, B1: credential management, provider migrations, RBAC tuples	IntegrationCredentialManagementAuthorizationTests, IntegrationCredentialSqliteTests, CurrentUserAccessServiceTests, LocalAuthenticationEndpointsTests, and the rendered account journey
A5, A6: OpenAPI security/taxonomy/version and Scalar proxy	OpenApiAndVersionEndpointsTests, WebAuthRoutesTests, and Playwright setup.spec.ts
B2: documented MCP Compose modes/origins/non-root access	tools/ci/test-mcp-compose-config.sh, AuthentikMcpOptionsValidatorTests, McpHttpHostTests, Compose CI jobs

Validation

Current head: 6449cdb62eaf7301229db5973d37789daa4a1499.

• Pull-request validation run #352 passed public disclosure, .NET, Playwright, Docker, Compose (SQLite and PostgreSQL), release rehearsal, layout/reference, and extracted-archive execution on Linux x64, Linux ARM64, and Windows x64.
• Managed PostgreSQL validation passed.
• The stale macOS-queued run was cancelled after the platform policy changed; macOS is intentionally outside the release payload and CI matrix.
• tools/release/test-publish-release-assets.sh passed locally, including missing files, partial uploads, reruns, conflicts, complete payload checks, and the supported-RID manifest.
• Focused local credential regression: dotnet test tests/Helpdesk.Tests/Helpdesk.Tests.csproj --no-build --filter 'FullyQualifiedName~IntegrationCredentialSqliteTests|FullyQualifiedName~IntegrationCredentialManagementAuthorizationTests' -v:minimal — 15 passed.

Owner smoke journey (disposable data)

1. Start a fresh local stack, complete setup, and sign in as an administrator.
2. Open Account → Integration credentials, create an organization-scoped API/MCP credential, and copy its one-time secret.
3. Use the API credential with the CLI or stdio server for helpdesk_auth, health, and a permitted business read.
4. Configure an HTTP MCP client with manual Authorization: Bearer rdk_... and the documented canonical resource; initialize, read, perform a confirmed permitted mutation, then verify a forbidden write/cross-organization read.
5. Revoke the credential in Account and confirm the next API/MCP request is denied.

Draft status

This remains a draft for owner review. No merge, tag, release, image/package publication, or deployment has been performed.