fix: broken detail views and tagging for 5 services

[DaviReisVieira]

Summary

Fixes #110

• AppSync, Cognito-IDP, EMR — 500 on resource detail: ID field extraction picked wrong field (Name before Id, or wrong case ApiId vs apiId). Fixed via _PREFERRED_ID_FIELD overrides.
• SES — 404 on detail: SES v1 has no single-identity describe API. Added custom handler aggregating verification + DKIM attributes.
• API Gateway — resources not listed: registry queried apigatewayv2 (HTTP APIs) but only REST APIs (v1) existed. Added rest_apis resource type.
• Tagging — Added tag read/write support for Cognito-IDP (via pool ARN), EMR (via ClusterId), and API Gateway REST (via ARN). SES v1 and AppSync on LocalStack don't support tagging.

Changes

File	What
backend/routes/resources.py	_PREFERRED_ID_FIELD entries, SES custom handler, REST API describe entry
backend/routes/stats.py	rest_apis in SERVICE_REGISTRY for apigateway
backend/routes/tags.py	Getter/setter functions + registry entries for 3 services
tests/test_tags_routes.py	Updated supported count (21→24) and writable count (20→23)
ui/dist/	Rebuilt frontend

Test plan

• python -m pytest tests/ -x — 288 passed
• npx tsc -b — clean
• Verified all 5 detail endpoints return data against LocalStack
• Verified tag getter/setter functions with mocked boto3 clients
• Verified API Gateway REST APIs appear in /api/stats and /api/resources/apigateway