docs(openspec): propose setup-foundation change

Add OpenSpec change for SPEC Phase 0 — Foundation with proposal,
design, capability specs, and implementation tasks. Populate
openspec/config.yaml with project context and artifact rules.

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

openspec/changes/setup-foundation/specs/health-check/spec.md

@@ -0,0 +1,24 @@
+## ADDED Requirements
+
+### Requirement: Public health endpoint responds without authentication
+
+The system SHALL expose `GET /up` as a public healthcheck endpoint that does not require authentication.
+
+#### Scenario: Application is healthy
+
+- **WHEN** a client sends `GET /up` while the application is running normally
+- **THEN** the system responds with HTTP 200 in a timely manner
+
+#### Scenario: Health endpoint exposes no secrets
+
+- **WHEN** a client sends `GET /up`
+- **THEN** the response MUST NOT include credentials, tokens, stack traces, or environment secrets
+
+### Requirement: Health endpoint reflects application failure
+
+The system SHALL return a failure status when the application cannot initialize properly.
+
+#### Scenario: Application cannot boot
+
+- **WHEN** the application fails to boot due to misconfiguration or missing dependencies
+- **THEN** the health endpoint MUST NOT return HTTP 200