Regenerate 2026-03-10 changelog with full commit set (installer, devcontainer
support, arc pr subcommands, --no-dotenv removal). Add 2026-03-11 changelog
for shadow branch run records and arc diff improvements. Update docs: CLI
reference (arc pr list/view/merge/close, --shortstat), devcontainers page
(replace placeholder with full content), run-configuration (devcontainer
field), checkpoints (per-node files on metadata branch), models catalog
(gemini-3.1-pro-preview-customtools). Improve preflight to show per-model
LLM checks instead of a single merged provider line.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
cfd7ea8c97
