test(drive): add coverage for fee calculation engine

[QuantumExplorer]

Summary

Adds 65 tests for rs-drive/src/fees/op.rs — the core fee calculation engine — which previously had 0 test coverage.

Section	Tests	What's covered
BaseOp::cost()	11	Spot-checks across all opcode categories
HashFunction methods	8	block_size, rounds, block_cost, base_cost for all 4 variants
FunctionOp::new_with_byte_count	9	Block/round calculations for various byte counts and hash functions
FunctionOp::cost	8	Saturating arithmetic, extreme fee versions
operation_cost()	4	All 4 match arms including error paths
combine_cost_operations	3	Filtering and summing mixed operation types
grovedb_operations_batch	8	Partitioning, consume, consume_with_leftovers
DriveCost::ephemeral_cost	14	Each cost component in isolation, overflow error handling

Test plan

• cargo test -p drive --lib -- fees::op — 65 passed
• cargo fmt --all clean

🤖 Generated with Claude Code

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ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 83fe64f5-589c-4981-9b6f-72c94cf8d5b9

📥 Commits

Reviewing files that changed from the base of the PR and between 7969880 and b0f456f.

⛔ Files ignored due to path filters (1)

• Cargo.lock is excluded by !**/*.lock

📒 Files selected for processing (2)

• packages/rs-drive/src/fees/op.rs
• packages/rs-scripts/Cargo.toml

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch test/drive-fees-coverage

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[thepastaclaw]

Review Gate

Commit: b0f456fc

• ⏳ Debounce: 18m ago (need 30m)

• ✅ CI checks: builds passed, 0/2 tests passed

• ✅ CodeRabbit review: comment found

• ✅ Off-peak hours: off-peak (11:36 AM PT Friday)

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[codecov]

Codecov Report

❌ Patch coverage is 98.77836% with 7 lines in your changes missing coverage. Please review.
✅ Project coverage is 80.26%. Comparing base (7011b62) to head (b0f456f).
⚠️ Report is 2 commits behind head on v3.1-dev.

Files with missing lines	Patch %	Lines
packages/rs-drive/src/fees/op.rs	98.77%	7 Missing ⚠️

Additional details and impacted files

@@ Coverage Diff @@## v3.1-dev #3429 +/- ##
============================================
+ Coverage 80.22% 80.26% +0.03% 
============================================
Files 2855 2855 Lines 281685 282623 +938 ============================================
+ Hits 225983 226842 +859 - Misses 55702 55781 +79 

Components	Coverage Δ
dpp	72.87% <ø> (-0.14%)	⬇️
drive	82.49% <98.77%> (+0.14%)	⬆️
drive-abci	86.70% <ø> (+0.03%)	⬆️
sdk	36.55% <ø> (ø)
dapi-client	79.06% <ø> (ø)
platform-version	∅ <ø> (∅)
platform-value	84.23% <ø> (ø)
platform-wallet	76.09% <ø> (ø)
drive-proof-verifier	55.26% <ø> (ø)

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