chore: project setup and tooling cleanup

[noahwaldner]

Summary

• Add project tooling: ESLint config, Prettier, .editorconfig, .nvmrc, .gitignore, CI workflow
• Add scripts/build.mjs build script
• Move remotion assets under tools/remotion/
• Remove CONTRIBUTING.md
• Fix npm run dev in CLAUDE.md — it now correctly starts the web server, not just prints CLI help

Test plan

• npm run dev starts the web server at http://localhost:3000
• npm run typecheck passes
• npm run lint passes

🤖 Generated with Claude Code

[Ark0N]

PR Review

Size: +4,698 / -4,404 across 61 files — ~95% is Prettier reformatting. ~12 substantive code changes buried in the noise, all safe.

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Behavioral Changes

1. npm run dev now starts the web server — Previously showed CLI help, now runs tsx src/index.ts web. CLAUDE.md updated to match, but the existing CRITICAL gotcha warning about this was softened to a plain "Note" — should either remove the gotcha entirely or keep the emphasis.

2. Remotion moved to devDependencies — @remotion/cli, @remotion/transitions, remotion moved from dependencies to devDependencies. Safe, remotion is tooling-only.

3. npm workspaces added — "workspaces": ["packages/*"] enables workspace support for packages/xterm-zerolag-input/.

4. Remotion files moved from remotion/ to tools/remotion/ — pure rename.

5. CONTRIBUTING.md removed.

Real Code Changes (Buried in Formatting)

Change	Files	Assessment
let → const (never reassigned)	session-lifecycle-log.ts, subagent-watcher.ts	✅ Correct
Spread operator assertion parens: ...(x as T)	respawn-controller.ts	✅ Prevents potential misparse
Generator methods modernized: *keys()	stale-expiration-map.ts	✅ Semantically identical, cleaner
interface Foo extends Bar {} → type Foo = Bar	ai-idle-checker.ts, ai-plan-checker.ts	✅ Equivalent
Unnecessary regex escapes removed in [...]	5 files	✅ Identical behavior
Arithmetic parenthesization	server.ts, tmux-manager.ts	✅ Identical, just clearer
eslint-disable comments for \x1b regexes	Multiple	✅ Required by new ESLint config

None touch critical paths (respawn, session management, state persistence, SSE).

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Issues to Address

1. .nvmrc / CI Node version mismatch — .nvmrc says 22, CI uses node-version: 20. Pick one. Will confuse contributors who run nvm use.

2. app.js excluded from both ESLint and Prettier — The 15K-line frontend file has zero automated quality checks while everything else does. Understandable for this PR's scope, but worth noting as a permanent gap.

3. 80-char print width is aggressive — The codebase was written with wider lines. This is the source of most of the diff noise and will affect all future diffs.

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Verdict

Safe to merge — no logic regressions. The formatting churn is large but clean.

[Ark0N]

Looks good overall — the tooling additions (ESLint, Prettier, CI, build script extraction) are solid and the ~12 real code changes are all improvements. No logic regressions found.

Two items to fix before merge:

1. .nvmrc says 22, CI uses 20 — pick one to avoid confusing nvm use
2. CLAUDE.md gotcha about npm run dev — now that it starts the web server, either remove the gotcha or update it to reflect the new behavior instead of softening the warning

Otherwise LGTM.