feat(coverage): add TypeScript source map generation for accurate coverage

- Import envAsBoolean from @socketsecurity/lib/env/helpers
- Enable source maps conditionally via COVERAGE env var
- Add rebuild step in cover.mjs with COVERAGE=true
- Matches socket-lib pattern for consistent behavior

When COVERAGE=true or COVERAGE=1:
- esbuild generates TypeScript source maps
- Coverage tools can map JS back to TS sources
- Improves coverage accuracy

Author: jdalton

.config/esbuild.config.mjs

@@ -11,6 +11,7 @@ import { parse } from '@babel/parser'
 import MagicString from 'magic-string'
 
 import { NODE_MODULES } from '@socketsecurity/lib/constants/paths'
+import { envAsBoolean } from '@socketsecurity/lib/env/helpers'
 import { getDefaultLogger } from '@socketsecurity/lib/logger'
 
 const __dirname = path.dirname(fileURLToPath(import.meta.url))
@@ -210,7 +211,8 @@ export const buildConfig = {
   platform: 'node',
   // Target Node.js 18+ features.
   target: 'node18',
-  sourcemap: false,
+  // Enable source maps for coverage (set COVERAGE=true env var)
+  sourcemap: envAsBoolean(process.env.COVERAGE),
   minify: false,
   treeShaking: true,
   // For bundle analysis

scripts/cover.mjs

@@ -14,6 +14,7 @@ import { fileURLToPath } from 'node:url'
 
 import { parseArgs } from '@socketsecurity/lib/argv/parse'
 import { getDefaultLogger } from '@socketsecurity/lib/logger'
+import { spawn } from '@socketsecurity/lib/spawn'
 import { printHeader } from '@socketsecurity/lib/stdio/header'
 
 import { runCommandQuiet } from './utils/run-command.mjs'
@@ -37,6 +38,23 @@ const { values } = parseArgs({
 printHeader('Test Coverage')
 logger.log('')
 
+// Rebuild with source maps enabled for coverage
+logger.info('Building with source maps for coverage...')
+const buildResult = await spawn('node', ['scripts/build.mjs'], {
+  cwd: rootPath,
+  stdio: 'inherit',
+  env: {
+    ...process.env,
+    COVERAGE: 'true',
+  },
+})
+if (buildResult.code !== 0) {
+  logger.error('Build with source maps failed')
+  process.exitCode = 1
+  process.exit(1)
+}
+logger.log('')
+
 // Run vitest with coverage enabled, capturing output
 // Filter out custom flags that vitest doesn't understand
 const customFlags = ['--code-only', '--type-only', '--summary']