fix: move npm-specific integration tests to npm/ directory

- Move integration/special-commands.test.js to npm/ since it tests bin/ccs.js
- This test was incorrectly categorized as cross-installation integration
- It specifically tests npm package functionality (bin/ccs.js)
- Remove empty integration/ directory and update package.json
- Final test counts: 37 native + 39 npm + 7 unit = 83 total tests

Clean final structure:
- native/     - Native installation tests only
- npm/        - npm package tests (including integration tests)
- shared/     - Shared utilities, fixtures, and unit tests

tests/integration/special-commands.test.js

@@ -1,45 +0,0 @@
-const assert = require('assert');
-const { execSync } = require('child_process');
-const path = require('path');
-
-describe('integration: special commands', () => {
-  const ccsPath = path.join(__dirname, '..', '..', 'bin', 'ccs.js');
-
-  it('shows version with --version', () => {
-    const output = execSync(`node ${ccsPath} --version`, { encoding: 'utf8' });
-    assert(output.includes('CCS (Claude Code Switch)'));
-    assert(/version \d+\.\d+\.\d+/.test(output));
-  });
-
-  it('shows version with -v', () => {
-    const output = execSync(`node ${ccsPath} -v`, { encoding: 'utf8' });
-    assert(output.includes('version'));
-  });
-
-  it('shows help with --help', function() {
-    this.timeout(5000);
-    // Note: Requires claude installation, so we just test that it doesn't crash
-    try {
-      const output = execSync(`node ${ccsPath} --help`, {
-        encoding: 'utf8',
-        stdio: ['ignore', 'pipe', 'ignore']
-      });
-      // If we get here, claude was found and help was shown
-    } catch (e) {
-      // Expected if claude is not installed
-      assert(e.message.includes('Claude CLI not found') || e.status === 1);
-    }
-  });
-
-  it('handles --install command', () => {
-    const output = execSync(`node ${ccsPath} --install`, { encoding: 'utf8' });
-    assert(output.includes('Installing CCS Commands and Skills'));
-    assert(output.includes('Feature not yet implemented'));
-  });
-
-  it('handles --uninstall command', () => {
-    const output = execSync(`node ${ccsPath} --uninstall`, { encoding: 'utf8' });
-    assert(output.includes('Uninstalling CCS Commands and Skills'));
-    assert(output.includes('Feature not yet implemented'));
-  });
-});