feat: add get_contract_config single-read configuration snapshot

[Tijesunimi004]

What

Add a ContractConfig struct and a get_contract_config(env) read entrypoint that returns all nine global settings in a single call, resolving issue #111.

Why

Fetching the contract's global state currently requires nine separate ledger reads (is_paused, is_allowlist_enabled, is_service_registration_required, get_max_requests_per_call, get_min_requests_per_call, get_max_requests_per_window, get_rate_window_seconds, get_schema_version, get_admin). These reads can be inconsistent across ledgers when the contract state changes between calls. A dashboard or health check panel now works with one call instead of nine.

Implementation

• ContractConfig is a #[contracttype] struct with nine fields, each field carrying the same default as the corresponding per-field getter when the storage slot is absent.
• get_contract_config is implemented by calling the nine existing getters internally via Self::getter(env.clone()), so the defaults and storage key logic cannot drift.
• The function is a pure read: no require_auth, no pause gate. It is callable before init (returns admin: None) and while paused.
• No existing getter is modified; the change is purely additive.

Tests

Ten new tests in contracts/escrow/src/test.rs:

• test_get_contract_config_defaults_on_fresh_contract — all fields at their defaults after init
• test_get_contract_config_matches_individual_getters — every field equals its per-field getter after config changes
• test_get_contract_config_reflects_pause_toggle — pause/unpause reflected
• test_get_contract_config_reflects_allowlist_toggle — allowlist toggle reflected
• test_get_contract_config_reflects_strict_registration_toggle — strict-registration toggle reflected
• test_get_contract_config_reflects_bounds_and_window — per-call bounds and rate-limit window reflected
• test_get_contract_config_readable_while_paused — pure read, no pause gate
• test_get_contract_config_before_init_admin_is_none — admin: None and numeric defaults before init
• test_get_contract_config_reflects_admin_after_rotation — new admin reflected after two-step handover
• test_get_contract_config_is_idempotent — two consecutive reads return identical structs

test result: ok. 181 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out

Security notes

• get_contract_config performs no writes and calls no auth check; it cannot be used to bypass any access control.
• Fields are populated by calling the existing getters, so their values are always consistent with what those getters would return for the same ledger state.
• The function does not expose any per-agent or per-service state, only global contract settings.

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[mikewheeleer]

thanks for the effort @Tijesunimi004! 🙏 i can't tie this to an issue assigned to you, and we merge from the assigned contributor to keep the campaign fair. please claim an open unassigned issue first, then open your PR. closing for now — hope to see it back 🙌

[mikewheeleer]

good stuff — thanks for picking it up 🙌