docs(readme): replace complex README with comprehensive navigation index #77

Job	Run time
Bilingual Documentation Sync	7s
ADR Numbering & Status	5s
Sensitive Information Scan	6s
MASTER_INDEX Navigation	7s
Markdown Lint & Style	24s
Internal & External Link Validation	2m 19s
Mermaid Diagram Syntax	30s
Documentation QA Report	6s
Documentation Quality Gate	2s
	3m 46s

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