Refactor knowledge.md into AGENTS.md + docs/ #5987

Job	Run time
build-and-check	2m 56s
test-integration-packages/billing	1m 5s
test-integration-cli	48s
test-integration-packages/internal	1m 8s
test-integration-common	43s
test-integration-packages/agent-runtime	50s
test-common	42s
test-integration-web	51s
test-web	53s
test-.agents	44s
test-cli	52s
test-packages/internal	1m 11s
test-packages/agent-runtime	48s
test-sdk	49s
test-packages/billing	53s
test-integration-sdk	1m 27s
	16m 40s

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