Add Biome linting, formatting, and developer experience setup (#13)

- Biome for TypeScript linting and formatting
- Lint step added to CI pipeline
- Auto-fix all existing lint/format issues across codebase
- VS Code settings with Biome as default formatter
- .env.example with ANTHROPIC_API_KEY placeholder
- CLAUDE.md with project architecture and conventions
- npm scripts: lint, lint:fix, format

Closes #8

Co-authored-by: unknown <that-github-user@github.com>
Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: 3 people

.env.example

@@ -0,0 +1,3 @@
+# Required: Anthropic API key (used by Claude Code CLI)
+# Get one at https://console.anthropic.com/
+ANTHROPIC_API_KEY=sk-ant-...

.github/workflows/ci.yml

@@ -29,6 +29,9 @@ jobs:
       - name: Install dependencies
         run: npm ci
 
+      - name: Lint
+        run: npm run lint
+
       - name: Build
         run: npm run build
 

.vscode/extensions.json

@@ -0,0 +1,5 @@
+{
+  "recommendations": [
+    "biomejs.biome"
+  ]
+}

.vscode/settings.json

@@ -0,0 +1,7 @@
+{
+  "editor.defaultFormatter": "biomejs.biome",
+  "editor.formatOnSave": true,
+  "[typescript]": {
+    "editor.defaultFormatter": "biomejs.biome"
+  }
+}

CLAUDE.md

@@ -0,0 +1,30 @@
+# thinktank — AI Coding Instructions
+
+## What this project is
+thinktank is an ensemble AI coding tool. It runs N parallel Claude Code agents on the same task in isolated git worktrees, then selects the best result via test execution and convergence analysis.
+
+## Architecture
+- `src/cli.ts` — CLI entry point (commander)
+- `src/commands/` — CLI commands (run, apply, list)
+- `src/runners/` — Agent runners (claude-code, future: cursor, copilot)
+- `src/scoring/` — Convergence analysis and recommendation
+- `src/utils/` — Git operations, terminal display
+
+## Code conventions
+- TypeScript strict mode, no `any` types
+- Use node:test for testing (not jest/vitest)
+- Error messages must be actionable: tell the user what to do
+- Keep functions small and focused
+- Prefer composition over inheritance
+
+## Commands
+- `npm run build` — compile TypeScript
+- `npm test` — run all tests
+- `npm run lint` — check with Biome
+- `npm run lint:fix` — auto-fix lint issues
+- `npx tsx src/cli.ts` — run CLI in dev mode
+
+## PR process
+- One issue per PR, always reference the issue
+- Branch naming: `issue-N-short-description`
+- Build + lint + tests must pass before merging

biome.json

@@ -0,0 +1,30 @@
+{
+  "$schema": "https://biomejs.dev/schemas/2.4.9/schema.json",
+  "linter": {
+    "enabled": true,
+    "rules": {
+      "recommended": true,
+      "correctness": {
+        "noUnusedImports": "warn"
+      }
+    }
+  },
+  "formatter": {
+    "enabled": true,
+    "indentStyle": "space",
+    "indentWidth": 2,
+    "lineWidth": 100
+  },
+  "assist": {
+    "actions": {
+      "source": {
+        "organizeImports": {
+          "level": "on"
+        }
+      }
+    }
+  },
+  "files": {
+    "includes": ["src/**"]
+  }
+}