Emit a configuration-change event from every rate-limit and per-call bound setter

[mikewheeleer]

Add observability events for limit and bound configuration changes

Description

The configuration setters in contracts/escrow/src/lib.rs — set_max_requests_per_call, set_min_requests_per_call, set_max_requests_per_window, set_rate_window_seconds, set_require_service_registration, set_allowlist_enabled — all mutate operational policy silently, emitting no event. Unlike set_service_price (which emits price_set) or pause, an indexer or security monitor has no on-chain signal when an operator tightens or loosens these limits. This issue adds a consistent config-change event to each, closing the observability gap for policy mutations.

Requirements and context

• Repository scope: Agentpay-Org/Agentpay-contracts only.
• Publish a topic-tagged event from each listed setter, e.g. cfg_set(symbol_short!("max_call"), value) style, or distinct topics per setter — pick a scheme with a single decodable schema and document it.
• Use symbol_short! topics (≤9 chars) and consistent data tuples; values that are u32/u64/bool should be encoded so one subscriber can decode all config events.
• Keep the change purely additive — do not alter the price_set or paused payloads, and do not reorder any existing logic.
• Document the full config-event catalogue (extending any existing events doc if present).

Suggested execution

• Fork the repo and create a branch
• git checkout -b feature/contracts-config-change-events
• Implement changes
  • Write code in: contracts/escrow/src/lib.rs — env.events().publish(...) in each config setter.
  • Write comprehensive tests in: contracts/escrow/src/test.rs — assert the event topic/data via env.events().all() for each setter.
  • Add documentation: document the config events in README.md.
  • Include NatSpec-style doc comments (///) matching the existing style in lib.rs.
  • Validate security: events expose no more than the state already does; topic lengths within Soroban symbol limits.
• Test and commit

Test and commit

• Run cargo fmt --all -- --check, cargo build, and cargo test.
• Cover edge cases: setting a value to its current value still emits, boolean toggles, large numeric values.
• Include the full cargo test output and a short security notes section in the PR description.

Example commit message

feat: emit config-change events from rate-limit and bound setters

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
• ⭐ This is a GrantFox OSS / Official Campaign task and may be rewarded. When your PR is merged you'll be prompted to rate the project — if this issue and the maintainers helped you ship, we'd be grateful for a 5-star rating. Clear questions in Discord and tidy, well-tested PRs are the fastest path to a merge and a reward.

[gloskull]

Hello, I have 4 years of experience delivering solutions for projects like this, covering backend, frontend, and smart contract development. After carefully reviewing your requirements, I have a clear understanding of the task and am confident in my ability to deliver a clean, efficient, and thoroughly tested solution on time. I prioritize code quality, maintainability, and industry best practices throughout the development process.
My PR will be submitted in under 10hours.

[yunus-dev-codecrafter]

Hi! I've carefully reviewed the entire task description and fully understand the requirements and expected outcome.
I have experience working on similar tasks and I'm confident I can complete this within about an hour. I'd be happy to take ownership of this issue and submit a clean, well-tested solution promptly.
If it's available, please assign it to me. Thank you!

[grantfox-oss]

🎉 This issue has been marked as completed on GrantFox!

@yunus-dev-codecrafter's PR #142 was approved and merged by @mikewheeleer.

🏆 @yunus-dev-codecrafter: You earned 40 FoxPoints for this contribution! Your current tier: Builder (2,231 total points). Track your full progress on GrantFox.

👏 Great work, @yunus-dev-codecrafter! Keep contributing to Agentpay-Org.