test: add get_stakers with zero balance flow

[arad-starkware]

This change is 

---

Note

Adds a flow test for get_stakers validating zero-balance/new staker visibility across epochs and updates the flow ideas doc.

• Tests:
  • Add get_stakers_zero_balance_flow_test in workspace/apps/staking/contracts/src/flow_test/test.cairo to validate get_stakers returns:
    • Empty set for current and next epoch after staking.
    • Inclusion with full STRK_WEIGHT_FACTOR and Option::None public key starting the following epoch, persisting thereafter.
• Docs:
  • Update flow_ideas.md under get_stakers by removing the zero-balance case entry.

^{Written by Cursor Bugbot for commit 82c2b26. This will update automatically on new commits. Configure here.}

[arad-starkware]

• test: add get_stakers 100% power test #34
• test: add get_stakers switch flow #33
• test: add get_stakers increase stake flow #32
• test: add get_stakers enable disable tokens flow #31
• test: add get stakers delegation undelegation flow #30
• add get_stakers btc and strk delegations flow #29
• test: add get_stakers exit action flow #28
• test: add get_stakers exit intent flow #27
• test: add get_stakers with zero balance flow #26 👈 (View in Graphite)
• main

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 95.39%. Comparing base (0d4c1ff) to head (82c2b26).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #26      +/-   ##
==========================================
- Coverage   95.74%   95.39%   -0.35%     
==========================================
  Files          47       45       -2     
  Lines       11159     9362    -1797     
==========================================
- Hits        10684     8931    -1753     
+ Misses        475      431      -44     

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[noa-starkware]

@noa-starkware reviewed 1 of 2 files at r1.
Reviewable status: 1 of 2 files reviewed, 1 unresolved discussion (waiting on @NirLevi-starkware)

---

workspace/apps/staking/contracts/src/flow_test/test.cairo line 1890 at r2 (raw file):

    let staking_consensus = system.staking.consensus_dispatcher();

    // Test balance with get_stakers

Suggestion:

Test same epoch.

[arad-starkware]

Reviewable status: 1 of 2 files reviewed, all discussions resolved (waiting on @NirLevi-starkware)

---

workspace/apps/staking/contracts/src/flow_test/test.cairo line 1890 at r2 (raw file):

    let staking_consensus = system.staking.consensus_dispatcher();

    // Test balance with get_stakers

Done

[noa-starkware]

Reviewable status: 1 of 2 files reviewed, all discussions resolved (waiting on @NirLevi-starkware)