feat(router-core): add batch route scoring

[Yasir-TechGuy]

Description

This PR addresses #635 by introducing a batch score-updating mechanism in router-core.

Previously, updating scores sequentially triggered a full $O(n)$ best-route recomputation via recompute_best_route() on every single update, causing massive CPU overhead during multi-route administrative updates.

This change adds set_route_scores_batch(), allowing administrators to submit multiple route score updates in a single transaction. The expensive recompute_best_route() function is now executed exactly once at the end of the entire batch process.

Key Changes

Types & Interfaces

• Introduced RouteScoreInput: A new #[contracttype] struct to facilitate safe input handling for batch configurations.
• Added set_route_scores_batch(): The core batch entry point requiring admin authentication.

🛡️ Fail-Fast & Atomic Execution

• Implemented a two-pass architecture to prevent partial updates.
  1. Validation Pass: The function scans the entire input list first. If any route inside the batch does not exist, it aborts early and returns RouterError::RouteNotFound.
  2. Execution Pass: Once validation succeeds, the state updates are committed, events are published, and recompute_best_route is called exactly once.

Bug Fixes & Refactoring

• Fixed overlapping discriminant values in RouterError (InvalidAddress changed from 10 to 12; RouteExpired changed from 10 to 13).
• Cleaned up scoring module calls by using Self::recompute_best_route(&env).

Test Coverage

Added comprehensive unit tests within mod tests:

• test_set_route_scores_batch: Verifies successful batch updates across multiple legitimate routes.
• test_set_route_scores_batch_fails_if_route_missing: Assures atomicity by checking that if a single route name is missing, the transaction fails completely and leaves prior scores untouched.

Fixes

Fixes #635

closes #635

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[Yasir-TechGuy]

Hi @Maki-Zeninn Please check it out.