feat(phase-2): implement domain verification system

Implements complete domain verification flow with:
- rel=me link verification service
- HTML fetching with security controls
- Rate limiting to prevent abuse
- Email validation utilities
- Authorization and verification API endpoints
- User-facing templates for authorization and verification flows

This completes Phase 2: Domain Verification as designed.

Tests:
- All Phase 2 unit tests passing
- Coverage: 85% overall
- Migration tests updated

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

src/gondulf/dependencies.py

@@ -0,0 +1,87 @@
+"""FastAPI dependency injection for services."""
+from functools import lru_cache
+
+from gondulf.config import Config
+from gondulf.database.connection import Database
+from gondulf.dns import DNSService
+from gondulf.email import EmailService
+from gondulf.services.domain_verification import DomainVerificationService
+from gondulf.services.html_fetcher import HTMLFetcherService
+from gondulf.services.rate_limiter import RateLimiter
+from gondulf.services.relme_parser import RelMeParser
+from gondulf.storage import CodeStore
+
+
+# Configuration
+@lru_cache
+def get_config() -> Config:
+    """Get configuration instance."""
+    return Config
+
+
+# Phase 1 Services
+@lru_cache
+def get_database() -> Database:
+    """Get singleton database service."""
+    config = get_config()
+    db = Database(config.DATABASE_URL)
+    db.initialize()
+    return db
+
+
+@lru_cache
+def get_code_storage() -> CodeStore:
+    """Get singleton code storage service."""
+    config = get_config()
+    return CodeStore(ttl_seconds=config.CODE_EXPIRY)
+
+
+@lru_cache
+def get_email_service() -> EmailService:
+    """Get singleton email service."""
+    config = get_config()
+    return EmailService(
+        smtp_host=config.SMTP_HOST,
+        smtp_port=config.SMTP_PORT,
+        smtp_from=config.SMTP_FROM,
+        smtp_username=config.SMTP_USERNAME,
+        smtp_password=config.SMTP_PASSWORD,
+        smtp_use_tls=config.SMTP_USE_TLS
+    )
+
+
+@lru_cache
+def get_dns_service() -> DNSService:
+    """Get singleton DNS service."""
+    return DNSService()
+
+
+# Phase 2 Services
+@lru_cache
+def get_html_fetcher() -> HTMLFetcherService:
+    """Get singleton HTML fetcher service."""
+    return HTMLFetcherService()
+
+
+@lru_cache
+def get_relme_parser() -> RelMeParser:
+    """Get singleton rel=me parser service."""
+    return RelMeParser()
+
+
+@lru_cache
+def get_rate_limiter() -> RateLimiter:
+    """Get singleton rate limiter service."""
+    return RateLimiter(max_attempts=3, window_hours=1)
+
+
+@lru_cache
+def get_verification_service() -> DomainVerificationService:
+    """Get singleton domain verification service."""
+    return DomainVerificationService(
+        dns_service=get_dns_service(),
+        email_service=get_email_service(),
+        code_storage=get_code_storage(),
+        html_fetcher=get_html_fetcher(),
+        relme_parser=get_relme_parser()
+    )