Add registry support for bun, uv, railway, docker compose

Context

Ran rtk discover --all --limit 10 --since 14 against 1,895 Claude Code sessions (14,189 bash commands). The scan surfaced frequent commands that rtk currently does not rewrite. Adding them to the registry would reclaim substantial tokens.

Top unhandled commands (14-day sample)

Command	Count	Example	Notes
bun run	599	bun run build 2>&1	Bun script runner, parallels pnpm run
uv run	424	uv run ruff check tests/test_scorer.py	uv Python runner
railway logs	208	railway logs --service dashboard 2>&1	Railway CLI — verbose tail output
docker compose	98	docker compose up canvas -d 2>&1	Distinct from docker (already handled)
railway variables	82	railway variables --service dashboard	Railway env var listing
bun typecheck	70	bun typecheck 2>&1	Same family as bun run
railway service	61	railway service list 2>&1	Railway service listing

Combined volume: ~1,540 invocations in 14 days from a single user. Conservative token estimate if rewrites match existing rtk pnpm/rtk docker/rtk tsc ratios: 200K–400K additional tokens saveable.

Suggested rewrite targets

1. rtk bun <subcmd> — mirror rtk pnpm behavior. Prioritize bun run, bun typecheck, bun install, bun test.
2. rtk uv — mirror the existing Python runner patterns. Focus on uv run (compiler/linter output is noisy).
3. rtk railway — verbose CLI output (logs especially). rtk railway logs should truncate/dedupe like rtk docker logs.
4. rtk docker compose — subcommand of existing rtk docker. Today docker exec is handled but docker compose falls through.

Environment

• rtk --version: 0.35.0
• OS: macOS (Darwin 25.4.0)
• Host: Claude Code with ~/.claude/hooks/rtk-rewrite.sh active

Happy to share the raw rtk discover --all --format json output if helpful.