Adopt eslint-config-agent in agent-runner (currently no ESLint at all) #101

What

agent-runner/ is the only JavaScript in this otherwise-Rust repository, and it has no ESLint setup at all — agent-runner/src/index.js (a ~215-line Node HTTP server handling HMAC-validated webhooks and spawning subprocesses) is currently never linted.

This proposes wiring in the shared eslint-config-agent config so that code gets the same baseline the rest of my JS/TS repos are on.

What it replaces

Nothing — there is no existing config to migrate. agent-runner/package.json has no devDependencies and no lint script. This is a from-zero adoption, not a swap.

Scope

Deliberately small and contained to agent-runner/:

• add eslint, eslint-config-agent and globals as devDependencies
• add agent-runner/eslint.config.js wiring in the shared config
• add a lint script
• ignore node_modules/ (the repo's .gitignore is Rust-oriented and doesn't cover it)

No Rust code, no CI workflow, and no src/index.js behaviour is touched.

Preset choice

Starting on eslint-config-agent/recommended-incremental — the divisive strict-mode rules disabled and everything else downgraded to warning level. On this file that reports 45 warnings and 0 errors, so pnpm lint exits 0 and the full backlog stays visible without a noisy behaviour-changing diff. The warnings (no-console on server startup logging, unicorn/prevent-abbreviations on req/res, no-restricted-syntax on direct process.env access, JSDoc formatting) can be burned down separately, then the preset promoted to recommended or the strict default.

Filed by the "Scout & wire eslint-config-agent adoption → Slack" moadim routine.