feat: add peer ids to each staker

[arad-starkware]

This change is 

---

Note

High Risk
High risk because it changes on-chain storage and public interfaces/events (including get_stakers return type), which can break downstream consumers and requires careful migration/compatibility validation.

Overview
Adds a new per-staker PeerId (u256) that can be set by stakers via set_peer_id, takes effect after K epochs, and is readable via get_current_peer_id; emits a new PeerIdSet event and introduces related validation/errors.

Extends the consensus API get_stakers to include Option<PeerId> alongside Option<PublicKey>, wires peer-id storage/lookup into staking.cairo, and updates the spec/docs accordingly.

Updates test utilities and flow/unit/fork tests to cover peer-id behavior (activation delay, pause/unstake/upgrade edge-cases) and to accommodate the expanded get_stakers tuple.

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[arad-starkware]

• refactor: extract common delayed field logic #102
• feat: add peer ids to each staker #100 👈 (View in Graphite)
• main

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[codecov]

Codecov Report

❌ Patch coverage is 97.12644% with 10 lines in your changes missing coverage. Please review.
✅ Project coverage is 95.90%. Comparing base (06d3d2e) to head (74cfb58).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/staking/tests/test.cairo	97.16%	6 Missing ⚠️
src/staking/staking.cairo	87.50%	3 Missing ⚠️
src/staking/tests/pause_test.cairo	83.33%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #100      +/-   ##
==========================================
- Coverage   95.91%   95.90%   -0.01%     
==========================================
  Files          43       43              
  Lines       10797    11115     +318     
==========================================
+ Hits        10356    10660     +304     
- Misses        441      455      +14     

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[NirLevi-starkware]

@NirLevi-starkware reviewed 13 files and all commit messages, and made 1 comment.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on arad-starkware).

[graphite-app]

Merge activity

• Apr 5, 2:41 PM UTC: This pull request can not be added to the Graphite merge queue. Please try rebasing and resubmitting to merge when ready.
• Apr 5, 2:41 PM UTC: Graphite disabled "merge when ready" on this PR due to: a merge conflict with the target branch; resolve the conflict and try again..
• Apr 6, 9:27 AM UTC: @arad-starkware merged this pull request with Graphite.