docs: credit openclaw/crawlkit + family in README

Add an Acknowledgements section calling out that fincrawl rides on
openclaw/crawlkit for the reusable mechanics and shares conventions
with the broader openclaw crawler family. crawlkit was previously
mentioned only inside docs/architecture.md; surfacing the credit on
the front page so readers (and sibling-repo agents) can find their
way back to the toolkit.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: altaywtf

README.md

@@ -156,6 +156,14 @@ tenant-data contribution boundary.
 
 Report vulnerabilities privately. See [Security](SECURITY.md).
 
+## Acknowledgements
+
+Built on [`openclaw/crawlkit`](https://github.com/openclaw/crawlkit) for
+reusable local-crawler mechanics (config, state, snapshot, mirror,
+SQLite plumbing). The agent-DX, release-pipeline, and tenant-store
+conventions are shared across the [`openclaw`](https://github.com/openclaw)
+crawler family.
+
 ## License
 
 MIT. See [License](LICENSE).