fix(config): migrate all hardcoded paths to getCcsDir() and improve validation

- Replace os.homedir() + '.ccs' with getCcsDir() across 14 instances in 13 files:
  version-command, model-config, openrouter-catalog, config-checks, disk-cache,
  aggregator, auth-middleware, shell-completion, shared-manager, recovery-manager,
  auto-repair, delegation-validator, claude-dir-installer, cliproxy executor
- Add isDirectory() validation for --config-dir argument in ccs.ts
- Make detectCloudSyncPath() case-insensitive for cloud provider matching
- Fix help-command.ts to use dynamic dirDisplay for all path references
- Add 5 new tests: setGlobalConfigDir precedence, relative path resolution,
  reset behavior, getCcsDirSource with --config-dir, case-insensitive detection
- Clean up unused os imports after migration

src/commands/help-command.ts

@@ -111,6 +111,10 @@ Run ${color('ccs config', 'command')} for web dashboard`.trim();
   );
   console.log('');
 
+  // Resolve display path for dynamic sections
+  const [dirSource] = getCcsDirSource();
+  const dirDisplay = dirSource === 'default' ? '~/.ccs' : getCcsDir();
+
   // Usage section
   console.log(subheader('Usage:'));
   console.log(`  ${color('ccs', 'command')} [profile] [claude-args...]`);
@@ -122,7 +126,7 @@ Run ${color('ccs config', 'command')} for web dashboard`.trim();
   // ═══════════════════════════════════════════════════════════════════════════
   printMajorSection(
     'API Key Profiles',
-    ['Configure in ~/.ccs/*.settings.json'],
+    [`Configure in ${dirDisplay}/*.settings.json`],
     [
       ['ccs', 'Use default Claude account'],
       ['ccs glm', 'GLM 4.6 (API key required)'],
@@ -267,8 +271,6 @@ Run ${color('ccs config', 'command')} for web dashboard`.trim();
   ]);
 
   // Configuration
-  const [dirSource] = getCcsDirSource();
-  const dirDisplay = dirSource === 'default' ? '~/.ccs' : getCcsDir();
   printConfigSection('Configuration', [
     ['Config File:', isUnifiedMode() ? `${dirDisplay}/config.yaml` : `${dirDisplay}/config.json`],
     ['Profiles:', `${dirDisplay}/profiles.json`],