Add Respectlytics to analytics tools list

Respectlytics is an open-source (AGPL-3.0 server, MIT SDKs), privacy-first
mobile app analytics platform. It differentiates from the existing web-focused
tools by targeting mobile apps with native SDKs for Swift, Kotlin,
Flutter, and React Native.

Key privacy properties:
- Only 5 fields stored per event (event_name, session_id, timestamp, platform, country)
- Session-based only — no persistent user IDs or device identifiers
- API architecturally rejects any extra data fields, including custom fields
- IP addresses processed transiently for country lookup, never stored
- Session IDs are RAM-only and rotate every 2 hours
- Self-hostable via Docker or available as managed cloud

README.md

@@ -154,6 +154,7 @@
 - [Umami](https://umami.is/) - A simple, fast, website analytics alternative to Google Analytics.
 - [Unidentified Analytics](https://unidentifiedanalytics.web.app/) - Naive ip-based tracking that works everywhere (web, command-line, email, etc). No account required. Developer friendly.
 - [Rybbit](https://rybbit.io) - Open-source and privacy-friendly alternative to Google Analytics that is 10x more intuitive.
+- [Respectlytics](https://respectlytics.com) - Open-source, privacy-first, session-based mobile app analytics with strict 5-field storage and no persistent user tracking.
 
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