docs: Add On-chain tracking page

[germartinez]

Context

This PR:

• Adds a new page for on-chain tracking.
• Points to the on-chain tracking page from Protocol Kit and Relay Kit guides.
• Removes on-chain tracking sections in existing guides and points to the new page.

[github-actions]

Branch preview

✅ Deployed successfully in branch deployment:

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

[github-actions]

Overall readability score: 31.31 (🟢 +0)

File	Readability
onchain-tracking.mdx	35.03 (-)
execute-transactions.mdx	40.73 (🔴 -0.23)
multichain-safe-deployment.mdx	34.71 (🟢 +0.7)
safe-deployment.mdx	25.51 (🟢 +1.5)
4337-safe-sdk.mdx	31.71 (🔴 -4.85)

View detailed metrics

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

File	Readability	FRE	GF	ARI	CLI	DCRS
onchain-tracking.mdx	35.03	29.48	14.03	18.9	14.28	7.74
	-	-	-	-	-	-
execute-transactions.mdx	40.73	40.92	14.87	18.9	11.56	7.3
	🔴 -0.23	🟢 +0.1	🟢 +0.09	🔴 -0.1	🔴 -0.23	🟢 +0.02
multichain-safe-deployment.mdx	34.71	34.39	14.83	20	13.18	7.65
	🟢 +0.7	🔴 -7.14	🟢 +0.3	🟢 +0.7	🟢 +0.18	🟢 +0.03
safe-deployment.mdx	25.51	32.46	16.52	21.7	13.94	8.41
	🟢 +1.5	🟢 +2.33	🟢 +0.49	🟢 +0.3	🔴 -0.18	🟢 +0.03
4337-safe-sdk.mdx	31.71	36.76	17.32	20.6	11.44	7.87
	🔴 -4.85	🔴 -2.44	🔴 -1.11	🔴 -1.2	🔴 -0.11	🔴 -0.2

Averages:

	Readability	FRE	GF	ARI	CLI	DCRS
Average	31.31	27.26	13.71	17.44	15.73	8.97
	🟢 +0	🔴 -0.02	🟢 +0	🔴 -0.01	🟢 +0	🟢 +0

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