refactor(auth): modularize auth-commands into commands/ directory

- extract create, list, show, remove, default command handlers

- extract types.ts with CommandContext and parseArgs

- slim auth-commands.ts from 725 to 235 lines (68% reduction)

- add barrel exports at commands/index.ts and auth/index.ts

src/auth/commands/remove-command.ts

@@ -0,0 +1,86 @@
+/**
+ * Remove Command Handler
+ *
+ * Removes a saved profile and its instance directory.
+ */
+
+import * as fs from 'fs';
+import * as path from 'path';
+import { initUI, color, ok, fail, info } from '../../utils/ui';
+import { InteractivePrompt } from '../../utils/prompt';
+import { isUnifiedMode } from '../../config/unified-config-loader';
+import { exitWithError } from '../../errors';
+import { ExitCode } from '../../errors/exit-codes';
+import { CommandContext, parseArgs } from './types';
+
+/**
+ * Handle the remove command
+ */
+export async function handleRemove(ctx: CommandContext, args: string[]): Promise<void> {
+  await initUI();
+  const { profileName, yes } = parseArgs(args);
+
+  if (!profileName) {
+    console.log(fail('Profile name is required'));
+    console.log('');
+    console.log(`Usage: ${color('ccs auth remove <profile> [--yes]', 'command')}`);
+    exitWithError('Profile name is required', ExitCode.PROFILE_ERROR);
+  }
+
+  // Check existence in both legacy and unified
+  const existsLegacy = ctx.registry.hasProfile(profileName);
+  const existsUnified = ctx.registry.hasAccountUnified(profileName);
+
+  if (!existsLegacy && !existsUnified) {
+    console.log(fail(`Profile not found: ${profileName}`));
+    exitWithError(`Profile not found: ${profileName}`, ExitCode.PROFILE_ERROR);
+  }
+
+  try {
+    // Get instance path and session count for impact display
+    const instancePath = ctx.instanceMgr.getInstancePath(profileName);
+    let sessionCount = 0;
+
+    try {
+      const sessionsDir = path.join(instancePath, 'session-env');
+      if (fs.existsSync(sessionsDir)) {
+        const files = fs.readdirSync(sessionsDir);
+        sessionCount = files.filter((f) => f.endsWith('.json')).length;
+      }
+    } catch (_e) {
+      // Ignore errors counting sessions
+    }
+
+    // Display impact
+    console.log('');
+    console.log(`Profile '${color(profileName, 'command')}' will be permanently deleted.`);
+    console.log(`  Instance path: ${instancePath}`);
+    console.log(`  Sessions: ${sessionCount} conversation${sessionCount !== 1 ? 's' : ''}`);
+    console.log('');
+
+    // Interactive confirmation (or --yes flag)
+    const confirmed =
+      yes || (await InteractivePrompt.confirm('Delete this profile?', { default: false })); // Default to NO (safe)
+
+    if (!confirmed) {
+      console.log(info('Cancelled'));
+      process.exit(0);
+    }
+
+    // Delete instance
+    ctx.instanceMgr.deleteInstance(profileName);
+
+    // Delete profile from appropriate config
+    if (isUnifiedMode() && existsUnified) {
+      ctx.registry.removeAccountUnified(profileName);
+    }
+    if (existsLegacy) {
+      ctx.registry.deleteProfile(profileName);
+    }
+
+    console.log(ok(`Profile removed: ${profileName}`));
+    console.log('');
+  } catch (error) {
+    exitWithError(`Failed to remove profile: ${(error as Error).message}`, ExitCode.GENERAL_ERROR);
+  }
+}