Extract shared admin-auth and pause-gate helpers to remove duplication

[mikewheeleer]

Refactor repeated admin-auth and pause checks into shared helpers

Description

Nearly every admin entrypoint in contracts/escrow/src/lib.rs repeats the same block: read DataKey::Admin, unwrap_or_else panic with NotInitialized, then admin.require_auth(). The pause check (get(&DataKey::Paused).unwrap_or(false) → panic #4) is likewise copy-pasted. This duplication is error-prone — a new entrypoint can easily forget a check. This issue centralises both into private helpers.

Requirements and context

• Repository scope: Agentpay-Org/Agentpay-contracts only.
• Add private helpers, e.g. fn require_admin(env: &Env) -> Address and fn ensure_not_paused(env: &Env), and route all existing entrypoints through them.
• Behaviour must be byte-for-byte identical: same error codes, same ordering of auth vs. pause checks, same panics.
• This is a pure refactor — no new public API, no semantic change; the existing test suite must pass unchanged.
• Add a short rationale comment explaining the helper pattern for future contributors.

Suggested execution

• Fork the repo and create a branch
• git checkout -b refactor/contracts-29-auth-pause-helpers
• Implement changes
  • Write code in: contracts/escrow/src/lib.rs — introduce helpers, replace duplicated blocks.
  • Write comprehensive tests in: contracts/escrow/src/test.rs — existing tests must pass; add a regression test confirming a representative entrypoint still panics identically when paused/unauthorized.
  • Add documentation: note the helper convention in a module comment.
  • Include NatSpec-style doc comments (///) on the helpers.
  • Validate security: no check accidentally dropped during extraction.
• Test and commit

Test and commit

• Run cargo fmt --all -- --check, cargo build, and cargo test.
• Cover edge cases: confirm NotInitialized (#3) and ContractPaused (#4) still fire from the helpers.
• Include the full cargo test output and a short security notes section in the PR description.

Example commit message

refactor: extract shared admin-auth and pause-gate helpers

Guidelines

• Minimum 95 percent test coverage for impacted modules.
• Clear, reviewer-focused documentation.
• Timeframe: 96 hours.

Community & contribution rewards

• 💬 Join the AgentPay community on Discord for questions, reviews, and faster merges: https://discord.gg/eXvRKkgcv
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