Fix coverage script to suppress spinner output in JSON/simple modes

The coverage:percent script was outputting spinner text after JSON output,
corrupting the JSON format when used with --json flag. This prevents proper
parsing by CI workflows and other programmatic consumers.

Changes:
- Only start/stop spinner in default output mode
- Suppress spinner completely when using --json or --simple flags
- Ensures clean JSON output for programmatic consumption

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: jdalton

scripts/get-coverage-percentage.mjs

@@ -31,17 +31,24 @@ async function logCoveragePercentage(argv) {
   // Get code coverage metrics (statements, branches, functions, lines).
   let codeCoverage
   try {
-    if (!existsSync(coverageJsonPath)) {
-      spinner.start('Generating coverage data...')
-    } else {
-      spinner.start('Reading coverage data...')
+    // Only show spinner in default output mode (not JSON or simple).
+    if (!argv.json && !argv.simple) {
+      if (!existsSync(coverageJsonPath)) {
+        spinner.start('Generating coverage data...')
+      } else {
+        spinner.start('Reading coverage data...')
+      }
     }
 
     codeCoverage = await getCodeCoverage()
 
-    spinner.stop()
+    if (!argv.json && !argv.simple) {
+      spinner.stop()
+    }
   } catch (error) {
-    spinner.stop()
+    if (!argv.json && !argv.simple) {
+      spinner.stop()
+    }
     logger.error('Failed to get code coverage:', error.message)
     throw error
   }