feat: update_current_epoch_block_rewards

[noa-starkware]

This change is 

---

Note

Introduce update_current_epoch_block_rewards with average block duration tracking and supporting errors/constants; update tests and docs accordingly.

• Reward Supplier:
  • Add update_current_epoch_block_rewards() to compute per-epoch block rewards (STRK/BTC); staking-only.
  • Track block timing via new storage: avg_block_duration, block_snapshot; initialize avg_block_duration in constructor.
  • Add internal set_avg_block_duration() with sanity checks; use BLOCK_DURATION_SCALE and SECONDS_IN_YEAR in rewards calc.
  • Extend interface (IRewardSupplier) and use mul_wide_and_div for precise math.
• Errors:
  • Add internal errors: INVALID_BLOCK_NUMBER, INVALID_BLOCK_TIMESTAMP.
  • Add reward supplier error: BLOCK_DURATION_OVERFLOW.
• Constants/Utils:
  • Add SECONDS_IN_YEAR (shared); introduce BLOCK_DURATION_SCALE, DEFAULT_AVG_BLOCK_DURATION.
  • Rename test constant AVG_BLOCK_TIME -> AVG_BLOCK_DURATION; update time advancement helpers accordingly.
• Docs:
  • Update spec to document update_current_epoch_block_rewards and clarify calculate_current_epoch_rewards usage.
• Tests:
  • Add tests for block rewards flow and assertion cases; adjust helpers to use AVG_BLOCK_DURATION.

^{Written by Cursor Bugbot for commit a2c750f. This will update automatically on new commits. Configure here.}

[codecov]

Codecov Report

❌ Patch coverage is 95.19231% with 5 lines in your changes missing coverage. Please review.
✅ Project coverage is 95.74%. Comparing base (9734730) to head (a2c750f).

Files with missing lines	Patch %	Lines
src/reward_supplier/reward_supplier.cairo	82.75%	5 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #63      +/-   ##
==========================================
- Coverage   95.77%   95.74%   -0.03%     
==========================================
  Files          42       42              
  Lines       10102    10203     +101     
==========================================
+ Hits         9675     9769      +94     
- Misses        427      434       +7     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[NirLevi-starkware]

Reviewable status: 0 of 10 files reviewed, 1 unresolved discussion (waiting on @noa-starkware)

---

src/reward_supplier/reward_supplier.cairo line 141 at r2 (raw file):

    #[abi(embed_v0)]
    impl RewardSupplierImpl of IRewardSupplier<ContractState> {
        fn calculate_current_epoch_rewards(self: @ContractState) -> (Amount, Amount) {

Can't we use the code here? it looks the same. maybe we need to split the update function? to calculate_current_block_rewards and a setter to the block avg, WDYT?
This happend only once during epoch, so preformance is not an issue.