test: expand test coverage for telemetry, multi-generation history.

[Agbelomo]

Refactor get_full_audit_state single-pass storage access, decouple telemetry resets, support multi-generation outage history, and validate prune_history_by_age

Closes #507
Closes #508
Closes #509
Closes #510

Summary

This PR addresses four technical debt items in the apexchainx_calculator contract across storage access efficiency, telemetry counter reset logic, outage history query semantics, and age-based retention pruning validation:

1. get_full_audit_state performs about ten redundant version checks and re-reads the same instance storage per delegated getter #507 - Single-Pass Storage Access for get_full_audit_state: Refactored get_full_audit_state in apexchainx_calculator/src/lib.rs to execute a single check_version(&env) check and read storage keys (ADMIN_KEY, OPERATOR_KEY, PENDING_ADMIN_KEY, PENDING_OP_KEY, PAUSED_KEY, PAUSE_INFO_KEY, STATS_KEY, HISTORY_KEY) directly in one pass. Optimized get_config_snapshot and build_config_snapshot to read CONFIG_KEY once.
2. The telemetry weekly reset wipes fresh violations: calc_stale OR violation_stale resets both lanes, losing a violation recorded a day ago #508 - Decoupled Telemetry Resets: Decoupled calc_stale and violation_stale counter reset logic in record_severity_telemetry (calculation.rs & lib.rs). Each lane counter is now evaluated and reset independently, ensuring fresh violation data survives stale calculation resets (and vice versa).
3. get_history_by_outage returns entries across config generations with no distinguishing signal: consumers cannot isolate the current decision #509 - Multi-Generation Outage History: Documented and verified get_history_by_outage ordering (oldest-first, latest decision last). Each entry carries its config_version_hash, enabling consumers to distinguish entries across configuration generations.
4. prune_history_by_age silently no-ops for min_age_seconds >= now: the cutoff saturates to 0 and no event fires, so callers cannot tell nothing was pruned #510 - prune_history_by_age Range Validation: Added explicit range validation to prune_history_by_age in history.rs and lib.rs. Invocations with min_age_seconds >= current_ledger_timestamp are rejected with Err(SLAError::InvalidInput) to prevent silent no-ops.

Changes Made

• apexchainx_calculator/src/lib.rs: Single-pass get_full_audit_state, optimized build_config_snapshot, decoupled telemetry reset, min_age_seconds validation, updated docstrings.
• apexchainx_calculator/src/calculation.rs: Decoupled calc_stale and violation_stale reset logic in record_severity_telemetry.
• apexchainx_calculator/src/history.rs: Added min_age_seconds >= now validation returning Err(SLAError::InvalidInput), updated get_history_by_outage docstring.
• apexchainx_calculator/src/tests.rs: Added unit tests test_get_full_audit_state_single_pass_efficiency, test_record_severity_telemetry_decoupled_lane_resets, test_get_history_by_outage_multi_generation_history, test_prune_by_age_rejects_min_age_equal_to_now, and test_prune_by_age_rejects_min_age_greater_than_now.

Verification

• cargo check --tests: PASSED
• cargo test: PASSED (all 594 test cases passing)

[usmanimamu17-create]

Test coverage looks great, merging.

[usmanimamu17-create]

LGTM, thanks!