feat: add gitea-deploy skill, tools, and sdlc foreground service rule

- skills/gitea-deploy/: new skill for Gitea deployment automation
- tools/: shared utility scripts
- skills/sdlc/SKILL.md: add Foreground Service Rule for long-running
  processes (background start + readiness polling pattern)

skills/gitea-deploy/assets/architecture.puml

@@ -0,0 +1,35 @@
+@startuml gitea-deploy-architecture
+skinparam componentStyle rectangle
+skinparam defaultFontName Arial
+skinparam backgroundColor #FAFAFA
+
+package "gitea-deploy Skill" {
+  component "SKILL.md\n(instructions)" as SKILL
+  component "evals/evals.json" as EVALS
+}
+
+package "Local Machine" {
+  component "git repo\n(project)" as REPO
+  component "SSH private key" as KEY
+}
+
+package "VPS" {
+  component "Docker Engine" as DOCKER
+  component "docker-compose.yml" as COMPOSE
+  database "Gitea Data\n(~/gitea/data)" as DATA
+  component "Gitea Container\n(:3000, :22)" as GITEA
+}
+
+actor Developer
+
+Developer --> SKILL : triggers skill
+SKILL --> KEY : uses for SSH auth
+SKILL --> DOCKER : installs if missing
+SKILL --> COMPOSE : uploads & runs
+COMPOSE --> GITEA : starts container
+GITEA --> DATA : persists data
+SKILL --> GITEA : initializes via REST API
+SKILL --> REPO : git remote add + push
+REPO --> GITEA : git push (SSH)
+SKILL --> Developer : reports URLs
+@enduml