docs: sync OpenSpec archives and propose foundation parity

Archive completed public-site and production-provider changes into main specs, remove duplicate active changes, and add complete-foundation-parity so Phase 0 staging and remaining foundation gaps block Phase 2 cleanly.

Co-authored-by: Cursor <cursoragent@cursor.com>

openspec/changes/complete-foundation-parity/specs/health-check/spec.md

@@ -0,0 +1,16 @@
+## ADDED Requirements
+
+### Requirement: Staging health and smoke use the public /up endpoint
+
+Staging healthchecks and post-deploy smoke MUST call `GET /up` without authentication and MUST treat a non-200 response as deployment failure (SPEC §15.5, §16.2). The health response MUST NOT expose secrets.
+
+#### Scenario: Staging healthcheck probes /up
+
+- **WHEN** Dokploy or the container runtime evaluates application health after deploy
+- **THEN** it MUST request `/up`
+- **AND** MUST require HTTP 200 before marking the service healthy
+
+#### Scenario: Smoke failure on /up fails the deploy gate
+
+- **WHEN** post-deploy smoke requests `/up` and receives a non-200 response
+- **THEN** the staging promotion MUST be considered failed