docs: new contribution guideline for client structure #5863

Job	Run time
Build / Build	8m 12s
Test Agent Local / test_agent_local	40m 41s
Test API / API Test Local	7m 59s
Test Packages / Test ./internal/billing	1m 44s
Test Packages / Test ./internal/encryption	1m 46s
Test Packages / Test ./internal/hash	1m 40s
Test Packages / Test ./internal/id	2m 56s
Test Packages / Test ./internal/keys	1m 47s
Test Packages / Test ./internal/resend	2m 23s
Test Packages / Test ./internal/clickhouse	4m 1s
Test Packages / Test ./packages/api	3m 31s
Test Packages / Test ./packages/cache	2m 41s
Test Packages / Test ./packages/hono	1m 49s
Test Packages / Test ./packages/nextjs	2m 21s
Test Packages / Test ./packages/rbac	2m 15s
	1h 25m 46s

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