build: add oxlint, oxfmt, commitlint, lefthook, knip, and editorconfig configs (#23)

## Summary
- Install oxlint, oxfmt, commitlint, lefthook, knip as dev dependencies
- Add `.oxlintrc.json` (correctness rules + React plugin)
- Add `.oxfmtrc.json` (double quotes, semicolons, 2-space indent, trailing commas)
- Add `commitlint.config.js` (conventional commits)
- Add `lefthook.yml` (pre-commit lint+format, commit-msg commitlint)
- Add `.editorconfig` and `knip.config.ts`
- Add scripts: `pnpm lint`, `pnpm format`, `pnpm format:check`, `pnpm knip`

Part 1/4 of [VA-851](https://linear.app/heygen/issue/VA-851/pre-migration-configure-eslint-prettier-and-conventional-commits)

## Test plan
- [x] `pnpm lint` runs (reports pre-existing errors, expected)
- [x] `pnpm format:check` runs (reports pre-existing diffs, expected)
- [x] `commitlint` validates and rejects messages correctly
- [x] lefthook hooks install via `pnpm run prepare`
- [x] `pnpm knip` runs

.editorconfig

@@ -0,0 +1,9 @@
+root = true
+
+[*]
+indent_style = space
+indent_size = 2
+end_of_line = lf
+charset = utf-8
+trim_trailing_whitespace = true
+insert_final_newline = true

.oxfmtrc.json

@@ -0,0 +1,8 @@
+{
+  "singleQuote": false,
+  "semi": true,
+  "useTabs": false,
+  "tabWidth": 2,
+  "trailingComma": "all",
+  "printWidth": 100
+}

.oxlintrc.json

@@ -0,0 +1,8 @@
+{
+  "$schema": "https://raw.githubusercontent.com/oxc-project/oxc/main/npm/oxlint/configuration_schema.json",
+  "categories": {
+    "correctness": "error"
+  },
+  "plugins": ["react", "typescript"],
+  "ignorePatterns": ["dist/", "coverage/", "node_modules/"]
+}

commitlint.config.js

@@ -0,0 +1,3 @@
+export default {
+  extends: ["@commitlint/config-conventional"],
+};

knip.config.ts

@@ -0,0 +1,23 @@
+import type { KnipConfig } from "knip";
+
+const config: KnipConfig = {
+  workspaces: {
+    "packages/cli": {
+      entry: ["src/cli.ts"],
+    },
+    "packages/core": {
+      entry: ["src/index.ts", "src/lint/index.ts", "src/compiler/index.ts"],
+    },
+    "packages/engine": {
+      entry: ["src/index.ts"],
+    },
+    "packages/producer": {
+      entry: ["src/index.ts", "src/server.ts"],
+    },
+    "packages/studio": {
+      entry: ["src/index.ts", "src/styles/tailwind-preset.ts"],
+    },
+  },
+};
+
+export default config;

lefthook.yml

@@ -0,0 +1,14 @@
+pre-commit:
+  parallel: true
+  commands:
+    lint:
+      glob: "*.{js,jsx,ts,tsx}"
+      run: oxlint {staged_files}
+    format:
+      glob: "*.{js,jsx,ts,tsx,json,css,md,yaml,yml}"
+      run: oxfmt --check {staged_files}
+
+commit-msg:
+  commands:
+    commitlint:
+      run: commitlint --edit "{1}"

package.json

@@ -9,11 +9,26 @@
     "studio": "pnpm --filter @hyperframes/studio dev",
     "build:hyperframes-runtime": "pnpm --filter @hyperframes/core build:hyperframes-runtime",
     "build:hyperframes-runtime:modular": "pnpm --filter @hyperframes/core build:hyperframes-runtime:modular",
-    "set-version": "tsx scripts/set-version.ts"
+    "set-version": "tsx scripts/set-version.ts",
+    "lint": "oxlint .",
+    "lint:fix": "oxlint --fix .",
+    "format": "oxfmt .",
+    "format:check": "oxfmt --check .",
+    "knip": "knip",
+    "prepare": "test -d .git && lefthook install || true"
+  },
+  "pnpm": {
+    "onlyBuiltDependencies": ["lefthook"]
   },
   "devDependencies": {
+    "@commitlint/cli": "^20.5.0",
+    "@commitlint/config-conventional": "^20.5.0",
     "@types/node": "^25.0.10",
     "concurrently": "^8.2.0",
+    "knip": "^6.0.3",
+    "lefthook": "^2.1.4",
+    "oxfmt": "^0.41.0",
+    "oxlint": "^1.56.0",
     "tsx": "^4.21.0",
     "typescript": "^5.0.0"
   }