feat(api): add Anthropic direct API key support

Support native Anthropic API keys (sk-ant-...) via `ccs api create --preset anthropic`.
Profiles use ANTHROPIC_API_KEY env var without BASE_URL, letting Claude CLI
authenticate natively with x-api-key header instead of proxy Bearer token.

- Add anthropic preset to provider catalog
- Branch profile-writer env structure (native vs proxy)
- Add validateAnthropicKey() preflight with x-api-key header
- Auto-detect api.anthropic.com URL in interactive flow
- Fix hasApiKey/isConfigured to recognize ANTHROPIC_API_KEY
- Update delegation-validator for native mode profiles
- Add Droid target API key fallback (ANTHROPIC_API_KEY)

Closes #688

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

tests/unit/api/profile-writer-anthropic.test.ts

@@ -0,0 +1,104 @@
+import { afterEach, beforeEach, describe, expect, it } from 'bun:test';
+import * as fs from 'fs';
+import * as os from 'os';
+import * as path from 'path';
+import { createApiProfile } from '../../../src/api/services/profile-writer';
+
+describe('profile-writer Anthropic direct', () => {
+  let tempHome = '';
+  let originalCcsHome: string | undefined;
+
+  beforeEach(() => {
+    tempHome = fs.mkdtempSync(path.join(os.tmpdir(), 'ccs-profile-writer-'));
+    originalCcsHome = process.env.CCS_HOME;
+    process.env.CCS_HOME = tempHome;
+  });
+
+  afterEach(() => {
+    if (originalCcsHome === undefined) {
+      delete process.env.CCS_HOME;
+    } else {
+      process.env.CCS_HOME = originalCcsHome;
+    }
+
+    if (tempHome && fs.existsSync(tempHome)) {
+      fs.rmSync(tempHome, { recursive: true, force: true });
+    }
+  });
+
+  it('creates native env structure for sk-ant- API key', () => {
+    const result = createApiProfile(
+      'anthropic-test',
+      '',
+      'sk-ant-api03-testkey123',
+      { default: 'claude-sonnet-4-5-20250929', opus: 'claude-opus-4-5-20251101', sonnet: 'claude-sonnet-4-5-20250929', haiku: 'claude-haiku-4-5-20251001' }
+    );
+
+    expect(result.success).toBe(true);
+
+    const settingsPath = path.join(tempHome, '.ccs', 'anthropic-test.settings.json');
+    const settings = JSON.parse(fs.readFileSync(settingsPath, 'utf8'));
+
+    // Native mode: ANTHROPIC_API_KEY present, no BASE_URL or AUTH_TOKEN
+    expect(settings.env.ANTHROPIC_API_KEY).toBe('sk-ant-api03-testkey123');
+    expect(settings.env.ANTHROPIC_BASE_URL).toBeUndefined();
+    expect(settings.env.ANTHROPIC_AUTH_TOKEN).toBeUndefined();
+    expect(settings.env.ANTHROPIC_MODEL).toBe('claude-sonnet-4-5-20250929');
+  });
+
+  it('creates native env structure for api.anthropic.com URL', () => {
+    const result = createApiProfile(
+      'anthropic-url',
+      'https://api.anthropic.com',
+      'some-key-123',
+      { default: 'claude-sonnet-4-5-20250929', opus: 'claude-sonnet-4-5-20250929', sonnet: 'claude-sonnet-4-5-20250929', haiku: 'claude-sonnet-4-5-20250929' }
+    );
+
+    expect(result.success).toBe(true);
+
+    const settingsPath = path.join(tempHome, '.ccs', 'anthropic-url.settings.json');
+    const settings = JSON.parse(fs.readFileSync(settingsPath, 'utf8'));
+
+    expect(settings.env.ANTHROPIC_API_KEY).toBe('some-key-123');
+    expect(settings.env.ANTHROPIC_BASE_URL).toBeUndefined();
+    expect(settings.env.ANTHROPIC_AUTH_TOKEN).toBeUndefined();
+  });
+
+  it('creates proxy env structure for non-Anthropic keys', () => {
+    const result = createApiProfile(
+      'proxy-test',
+      'https://api.z.ai/api/anthropic',
+      'ghp_testkey123',
+      { default: 'glm-5', opus: 'glm-5', sonnet: 'glm-5', haiku: 'glm-5' }
+    );
+
+    expect(result.success).toBe(true);
+
+    const settingsPath = path.join(tempHome, '.ccs', 'proxy-test.settings.json');
+    const settings = JSON.parse(fs.readFileSync(settingsPath, 'utf8'));
+
+    // Proxy mode: BASE_URL + AUTH_TOKEN, no ANTHROPIC_API_KEY
+    expect(settings.env.ANTHROPIC_BASE_URL).toBe('https://api.z.ai/api/anthropic');
+    expect(settings.env.ANTHROPIC_AUTH_TOKEN).toBe('ghp_testkey123');
+    expect(settings.env.ANTHROPIC_API_KEY).toBeUndefined();
+  });
+
+  it('preserves OpenRouter ANTHROPIC_API_KEY blank behavior', () => {
+    const result = createApiProfile(
+      'openrouter-test',
+      'https://openrouter.ai/api',
+      'sk-or-testkey',
+      { default: 'anthropic/claude-opus-4.5', opus: 'anthropic/claude-opus-4.5', sonnet: 'anthropic/claude-opus-4.5', haiku: 'anthropic/claude-opus-4.5' }
+    );
+
+    expect(result.success).toBe(true);
+
+    const settingsPath = path.join(tempHome, '.ccs', 'openrouter-test.settings.json');
+    const settings = JSON.parse(fs.readFileSync(settingsPath, 'utf8'));
+
+    // OpenRouter: proxy mode with ANTHROPIC_API_KEY explicitly blank
+    expect(settings.env.ANTHROPIC_BASE_URL).toBe('https://openrouter.ai/api');
+    expect(settings.env.ANTHROPIC_AUTH_TOKEN).toBe('sk-or-testkey');
+    expect(settings.env.ANTHROPIC_API_KEY).toBe('');
+  });
+});