v0.0.3

Changes since v0.0.1

• Extract shared base image (sandbox-base) for system packages, Go, Go tools, and Node.js
• Pin major Go tool versions (gopls v0.21.1, delve v1.24.2, golangci-lint v2.11.3) and RTK
• Add RTK to codex sandbox image
• Add ~/.local/bin to PATH for RTK in both sandboxes
• CI workflow now builds base first, then claude/codex in parallel
• Add standalone usage docs with credential mounting examples
• Add image verification test script with optional live smoke tests
• Add AGENTS.md, CLAUDE.md, .gitignore