Soroban contract pause/circuit-breaker pattern audit + implementation

[truthixify]

Tier: L (1-2 weeks) Type: feature

Context

The governance doc (#37) flagged pause/circuit-breaker as a trade-off to decide. Make the call per-contract and implement consistently using a shared pattern.

Scope

• Audit each Stellar contract: should it have a pause function?
• For ones that should: implement OZ-style Pausable pattern (custom for Soroban)
• Admin-only pause/unpause (governed by upgrade authority)
• Tests cover paused vs unpaused behavior
• Update MAINNET_READINESS.md with pause posture per contract

Acceptance criteria

• Audit decision documented per contract
• Pausable contracts have full test coverage
• stellar/PAUSE.md describes the pattern and per-contract status
• Demo/SDK follow-up filed for how to surface pause state to users

Files to start with

• All stellar/*/src/lib.rs
• stellar/GOVERNANCE.md