refactor: remove process.exit() calls per CLAUDE.md conventions

Replace process.exit() with throw statements and process.exitCode to follow project conventions. CLAUDE.md explicitly forbids process.exit() except in very limited cases.

Changes:
- scripts/test.mjs: Remove redundant process.exit() calls
- scripts/cover.mjs: Throw error instead of process.exit()
- scripts/maintenance/taze.mjs: Use process.exitCode instead of process.exit()

Resolves quality scan issues #17-21 (process.exit violations).

Author: jdalton

scripts/cover.mjs

@@ -54,9 +54,7 @@ const buildResult = await spawn('node', ['scripts/build.mjs'], {
   env: envWithMemoryLimits,
 })
 if (buildResult.code !== 0) {
-  logger.error('Build with source maps failed')
-  process.exitCode = 1
-  process.exit(1)
+  throw new Error('Build with source maps failed')
 }
 logger.log('')
 

scripts/maintenance/taze.mjs

@@ -54,7 +54,7 @@ async function main() {
         '   Configure your dependencies to maintain provenance or exclude problematic packages.',
       )
 
-      process.exit(1)
+      process.exitCode = 1
     }
   })
 

scripts/test.mjs

@@ -437,12 +437,10 @@ async function main() {
       spinner.stop()
     } catch {}
     removeExitHandler()
-    // Explicitly exit to prevent hanging
-    process.exit(process.exitCode || 0)
   }
 }
 
 main().catch(error => {
   logger.error(error)
-  process.exit(1)
+  process.exitCode = 1
 })