feat: expand modern service dictionaries

[techgaun]

Summary

• add focused ai, identity, and observability dictionaries
• cover current AI providers, vector platforms, identity systems, and secret managers
• add managed database credentials for Neon, PlanetScale, Upstash, MongoDB Atlas, CockroachDB, ClickHouse, and Databricks
• expand hosting and CI/CD coverage for Netlify, Railway, Render, Fly.io, Firebase, CircleCI, Buildkite, Azure DevOps, and Bitbucket
• detect Kubernetes client keys, Terraform credential files, and additional private-key formats
• regenerate the backward-compatible aggregate dictionary
• document authoritative credential sources and update category guidance

The catalog now contains 186 unique dorks across 10 categories, up from 127 across 7 categories.

Verification

• python3 -m unittest discover -s tests -v (29 tests)
• aggregate matches all categorized dictionaries
• generated aggregate is current
• no duplicate dorks
• balanced quoting and whitespace checks
• git diff --check

Dependency

This PR is intentionally stacked on #70 and should be retargeted to main after #70 merges.