Implement admin controls for yield rate and supported token registry

[BigNathan1]

Summary

Closes #837

Adds governance/admin configuration controls to the inheritance contract:

• initialize and read the contract admin
• transfer admin control to a new address
• update the global base yield rate in basis points
• add and remove supported token addresses from the registry
• query supported token status

Configuration mutations are restricted to the stored admin signature and emit contract events for admin, yield, and token registry changes.

Tests

Added unit coverage for:

• admin initialization and one-time initialization guard
• global yield rate updates and invalid rate rejection
• admin-only enforcement for yield, token registry, and admin transfer operations
• supported token add/remove state changes
• duplicate token and missing token errors
• emitted configuration events

Note: cargo test -p inheritance-contract could not be run locally because cargo is unavailable in this environment.

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[ONEONUORA]

@BigNathan1
pls make implementation to pass cI checks

[ONEONUORA]

@BigNathan1
Update on this Pr
you will be unassign in 6hrs

[ONEONUORA]

@BigNathan1
Pls update on this PR