feat: add article AI assistant and visibility analytics

[yaojingang]

Summary

• add guided article generation with title selection, streaming output, knowledge-base evidence, and source-title traceability
• add configurable Doubao Search/Ark and DeepSeek visibility collection, source records, analytics, and a production collection command
• route visibility HTTP calls through the unified safe outbound gateway with strict HTTPS host-boundary validation
• centralize atomic, date-aware model/provider quotas across article, worker, embedding, knowledge, URL analysis, visibility, and connection-test paths
• prevent API keys from entering flashed form input and rate-limit sensitive connection-test endpoints
• include localized admin UI, migrations, demo data, automated tests, and implementation documentation

Review fixes

• preserve quota reservations across midnight with date-bound reservation handles
• require stored API keys before model bindings can be activated
• link both manual and Worker-generated articles to their selected source title
• synchronize with merged PRs test: enforce release version mapping #69 and feat: 增加网站备案信息设置 #71

Verification

• full PHPUnit suite: 1,037 tests, 8,416 assertions
• Composer validation passed
• production frontend build passed
• Laravel Pint passed for all changed PHP files
• fresh SQLite migration passed in the test environment
• Gitleaks scanned the exact origin/main..HEAD range with no findings
• GitHub has no configured status checks for this pull request