docs(openspec): add OpenSpec changes for FN-005, FN-006, FN-008, FN-009, FN-010

- Add frontend-foundation change (FN-005) with 46 tasks
- Add deployment-config change (FN-006) with 27 tasks
- Add runfusion-poc/opencode-poc change (FN-008) with 25 tasks
- Add config-secrets change (FN-009) with 31 tasks
- Add codeserver-spawn change (FN-010) with 38 tasks
- Include project specsheet and configuration
- Archive completed deployment-config change

openspec/changes/deployment-config/specs/portainer-deployment/spec.md

@@ -0,0 +1,22 @@
+## ADDED Requirements
+
+### Requirement: Stack deploys via Portainer
+The system SHALL provide a Portainer-compatible stack definition.
+
+#### Scenario: Portainer stack file
+- **WHEN** an operator deploys via Portainer
+- **THEN** they can paste the stack definition into Portainer's stack editor
+- **AND** Portainer can pull and deploy all services
+
+#### Scenario: Environment variables in Portainer
+- **WHEN** the stack is deployed via Portainer
+- **THEN** environment variables are configured in Portainer's UI
+- **AND** the stack references these variables
+
+### Requirement: Deployment documentation is complete
+The system SHALL provide operator documentation for deployment.
+
+#### Scenario: Deployment guide
+- **WHEN** an operator reads docs/deployment.md
+- **THEN** they find step-by-step instructions for Portainer deployment
+- **AND** prerequisites and assumptions are clearly stated