Turn ENTITY-FINANCE into a v3.4 developer landing page

[blackmore-technology-group]

Changes

• keeps the existing release binding and verification command intact;
• adds a clear explanation of what the Finance package is for;
• surfaces the ISO 20022, FIX and LEI mapping context from ENTITY v3.4.0;
• explains the deployment flow and required organization-specific facts;
• adds direct links back to the core release, developer portal and engineering evidence;
• preserves the boundary that mappings do not establish regulatory compliance, settlement finality or accounting fair value.

No package logic or release evidence is changed.