docs(README): category-first hero, honest DOCX claim, "When to use" b… #70

Job	Run time
Architecture and Documentation Guards	36s
Weekly Benchmark Diff	0s
Build and run tests (JDK 17)	1m 5s
Build and run tests (JDK 21)	46s
Build and run tests (JDK 25)	1m 0s
Performance Smoke Check	0s
Examples Generation Smoke Test	58s
	4m 25s

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