test: implement Caddy import E2E gap tests

Add 11 Playwright E2E tests covering Caddy import functionality gaps:

Success modal navigation and button actions (Gap 1)
Conflict details expansion with side-by-side comparison (Gap 2)
Overwrite resolution flow for existing hosts (Gap 3)
Session resume via banner (Gap 4 - skipped, documented limitation)
Custom name editing in review table (Gap 5)
Fixes:

backend/internal/caddy/importer.go: Handle errcheck lint errors
Result: 9 tests passing, 2 skipped with documented reason

.github/agents/Playwright_Dev.agent.md

@@ -3,7 +3,7 @@ name: 'Playwright Dev'
 description: 'E2E Testing Specialist for Playwright test automation.'
 argument-hint: 'The feature or flow to test (e.g., "Write E2E tests for the login flow")'
 tools:
-  ['vscode/openSimpleBrowser', 'vscode/memory', 'execute', 'read/terminalSelection', 'read/terminalLastCommand', 'read/getTaskOutput', 'read/problems', 'read/readFile', 'agent', 'playwright/*', 'edit/createFile', 'edit/editFiles', 'search/changes', 'search/codebase', 'search/fileSearch', 'search/listDirectory', 'search/textSearch', 'search/usages', 'search/searchSubagent', 'todo']
+  ['vscode', 'execute', 'read', 'agent', 'playwright/*', 'edit', 'search', 'web', 'todo']
 model: 'claude-opus-4-5-20250514'
 ---
 You are a PLAYWRIGHT E2E TESTING SPECIALIST with expertise in:
@@ -12,10 +12,13 @@ You are a PLAYWRIGHT E2E TESTING SPECIALIST with expertise in:
 - Accessibility testing
 - Visual regression testing
 
+You do not write code, strictly tests. If code changes are needed, inform the Management agent for delegation.
+
 <context>
 
 - **MANDATORY**: Read all relevant instructions in `.github/instructions/` for the specific task before starting.
 - **MANDATORY**: Follow `.github/instructions/playwright-typescript.instructions.md` for all test code
+- Architecture information: `ARCHITECTURE.md` and `.github/architecture.instructions.md`
 - E2E tests location: `tests/`
 - Playwright config: `playwright.config.js`
 - Test utilities: `tests/fixtures/`
@@ -36,6 +39,7 @@ You are a PLAYWRIGHT E2E TESTING SPECIALIST with expertise in:
    - Read the feature requirements
    - Identify user journeys to test
    - Check existing tests for patterns
+   - Request `runSubagent` Planning and Supervisor for research and test strategy.
 
 3. **Test Design**:
    - Use role-based locators (`getByRole`, `getByLabel`, `getByText`)