docs(b20): add integration architecture

[rayyan224]

Summary

• add a B20 Integration Architecture specification page
• add the page to B20 navigation and the overview, replacing its redirect
• regenerate the LLM indexes

Testing

• node scripts/validate-docs-structure.js
• npm test
• git diff --check

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Project	Status	Preview	Updated
base	🟢 Ready	View Preview	Oct 1, 2026, 2:58 PM

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[cb-heimdall]

🟡 Heimdall Review Status

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Reviews	🟡 0/1	Denominator calculation Show calculation 1 if user is bot 0 1 if user is external 0 2 if repo is sensitive 0 From .codeflow.yml 1 Additional review requirements Show calculation Max 0 0 From CODEOWNERS 0 Global minimum 0 Max 1 1 1 if commit is unverified 0 Sum 1

[cb-heimdall]

🟡 Heimdall Review Status

Requirement	Status	More Info
Reviews	🟡 0/1	Denominator calculation Show calculation 1 if user is bot 0 1 if user is external 0 2 if repo is sensitive 0 From .codeflow.yml 1 Additional review requirements Show calculation Max 0 0 From CODEOWNERS 0 Global minimum 0 Max 1 1 1 if commit is unverified 0 Sum 1