docs(sdk): React native passkeys tutorial

[yagopv]

Context

This PR adds a new tutorial to the advanced passkeys guides, teaching Safe developers how to work with React Native and Safe contracts, as well as how to add passkeys signers.

As a companion to this tutorial, we are introducing two new repositories:

• The React Native app
• The Express project to serve the required files that enable passkeys to function on mobile devices

[github-actions]

Branch preview

✅ Deployed successfully in branch deployment:

https://react_native_passkeys--docs.review.5afe.dev

[github-actions]

Overall readability score: 30.9 (🟢 +0.11)

File	Readability
react-native.mdx	61.98 (-)

View detailed metrics

🟢 - Shows an increase in readability
🔴 - Shows a decrease in readability

File	Readability	FRE	GF	ARI	CLI	DCRS
react-native.mdx	61.98	47.69	10.04	10.7	11.42	7.38
	-	-	-	-	-	-

Averages:

	Readability	FRE	GF	ARI	CLI	DCRS
Average	30.9	26.92	13.63	17.74	15.81	8.96
	🟢 +0.11	🟢 +0.07	🟢 +0.01	🟢 +0.02	🟢 +0.02	🟢 +0.01

View metric targets

Metric	Range	Ideal score
Flesch Reading Ease	100 (very easy read) to 0 (extremely difficult read)	60
Gunning Fog	6 (very easy read) to 17 (extremely difficult read)	8 or less
Auto. Read. Index	6 (very easy read) to 14 (extremely difficult read)	8 or less
Coleman Liau Index	6 (very easy read) to 17 (extremely difficult read)	8 or less
Dale-Chall Readability	4.9 (very easy read) to 9.9 (extremely difficult read)	6.9 or less