init: project structure, .gitignore, .env.example, runners.conf.example

- .gitignore: excludes .env, runners.conf, certs, temp files, editor files
- .env.example: all configuration variables with sections and descriptions
- runners.conf.example: dynamic runner definition format (pipe-delimited)
- PLAN.md: comprehensive implementation plan with DoD for all 18 milestones
- CLAUDE.md: project conventions and instructions

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.gitignore

@@ -0,0 +1,22 @@
+# Secrets — never commit
+.env
+runners.conf
+*.pem
+*.key
+*.crt
+
+# macOS
+.DS_Store
+
+# Temp files from script runs
+/tmp/
+*.log
+
+# Backup archives
+*.zip
+
+# Editor / IDE
+.vscode/
+.idea/
+*.swp
+*~