fix: enforce max lockout

[SWvheerden]

No description provided.

[Copilot]

Pull request overview

This PR hardens UTXO locking by enforcing a maximum lock duration (365 days) and replacing potentially panicking chrono arithmetic with checked, total helpers—preventing mutex poisoning and process-wide lockout outages from untrusted inputs.

Changes:

• Introduces MAX_SECONDS_TO_LOCK_UTXOS with validation + a checked lock_expiry_at(..) helper and adds tests for bounds and poison recovery.
• Validates lock duration at API boundaries (and within the locker) and maps invalid durations to HTTP 400.
• Updates OpenAPI to document/enforce the maximum lock duration.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
openapi.json	Adds maximum constraints and updates descriptions for lock-duration fields in the published OpenAPI spec.
minotari/src/transactions/manager.rs	Switches to checked lock-expiry computation to avoid chrono overflow panics.
minotari/src/transactions/fund_locker.rs	Adds max-duration enforcement, total expiry calculation, poison-recovery behavior, and tests covering the new guarantees.
minotari/src/api/error.rs	Maps InvalidLockDuration into a client-facing 400 Bad Request.
minotari/src/api/accounts/params.rs	Centralizes request default constants and clarifies serde-default behavior when null is provided.
minotari/src/api/accounts/fund_lock.rs	Validates lock duration early, handles explicit null defaults safely, and documents maximum via schema annotations.
minotari/src/api/accounts/burn.rs	Validates lock duration for burn requests and documents maximum via schema annotations.

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