add automated relay count tracking with dual trend charts (#8)

* Add relay count tracking workflow with dual charts

This commit adds:
- New GitHub workflow to track relay counts
- Two charts: BitChat-compatible relays and total functioning relays
- Extended history for both charts (70 days)
- Project structure improvements with scripts and assets directories
- Updated documentation in README.md and other files
- Dependencies in requirements.txt

* Remove overlapping data point labels from relay count charts

* Add .venv to gitignore

* Add relay location maps and automation workflow

* Improve relay maps with proper world map backgrounds using cartopy

* Add relay location map to README

* update readme

assets/README.md

@@ -0,0 +1,14 @@
+# Georelays Assets
+
+This directory contains generated assets for the Georelays project:
+
+## bitchat_relay_count_chart.png
+
+A chart showing the history of the number of BitChat-compatible relays (supporting kind 20000 events) in the `nostr_relays.csv` file over time.
+
+## total_relay_count_chart.png
+
+A chart showing the history of the total number of functioning relays discovered in the `relay_discovery_results.json` file over time.
+
+These charts are automatically generated by the GitHub workflow after each update to the relay data.
+They track the last 30 changes to the relay lists and plot them on time series graphs.