fix(tholos-v2): bound max_total_weight to max_position ratio at initialize (#168)

[s6pa1rta3n-lab]

Summary

Closes #168.

This change adds Sybil resistance bounding to TholosV2::initialize by constraining max_total_weight relative to max_position:

• Introduces MAX_TOTAL_WEIGHT_TO_POSITION_RATIO = 10.
• Enforces max_total_weight <= max_position.checked_mul(MAX_TOTAL_WEIGHT_TO_POSITION_RATIO).unwrap_or(i128::MAX).
• Adds error variant Error::InvalidWeightRatio = 37 returned when the ratio bound is violated.
• Adds comprehensive unit tests in contracts/tholos-v2/src/test.rs validating that initialize rejects configurations exceeding the ratio bound and accepts configurations at the exact ratio boundary.
• Adjusts test_register_exceeds_max_position_fails parameterization to satisfy the ratio constraint while verifying PositionExceedsMax.
• Updates docs/src/CONTRACT_V2.md with the new error variant, updated policy parameter descriptions, and an explicit analysis of Sybil resistance mechanics and residual plutocratic risk.

Economic and Sybil Analysis

In Tholos v2, max_position caps individual voter stake while max_total_weight caps total bonded stake W. Without a ratio constraint, an attacker with large capital can split into many positions of size max_position and dominate total voting weight cheaply if max_total_weight is set arbitrarily large relative to max_position. Capping the ratio to 10 limits the round to at most 10 maximum-sized positions, forcing any single Sybil attacker seeking a strict majority (>50% of W) to split and coordinate across at least 6 separate maximum-stake accounts. As documented, linear stake-weighting without external identity verification cannot eliminate plutocratic control by a >50% coalition; this ratio bound establishes a concrete capital-fragmentation lower bound while preserving operational flexibility.

Issue Stipulations & Compliance Checklist

• Bound max_total_weight as a function of max_position during contract initialization.
• Return dedicated error variant InvalidWeightRatio (variant 37).
• Add unit test asserting InvalidWeightRatio when max_total_weight > max_position * 10.
• Add unit test asserting initialization success when max_total_weight == max_position * 10.
• Document InvalidWeightRatio in docs/src/CONTRACT_V2.md.
• Document Sybil resistance rationale and residual plutocratic risk in docs/src/CONTRACT_V2.md.
• Maintain zero regression across all existing contract test suites.

Test plan

• cargo fmt --check passes cleanly.
• shellcheck -x scripts/*.sh scripts/lib/*.sh passes cleanly.
• cargo clippy --workspace --all-targets -- -D warnings passes with zero warnings.
• cargo test --workspace passes (all 109 tests in tholos-v2, 69 in tholos).
• cargo build --workspace --lib --target wasm32v1-none --release --locked builds successfully.
• docs/src/CONTRACT_V2.md updated with public error specification and ratio constraints.

Payout Routing

• EVM (Base/Arbitrum/Polygon/ETH): 0xF46C9F6d70C50BF81ef3588AB523a90a594a2F89
• Stellar: GCL6OXAMLD75BMTINA6EMRUDWK5THQUSHMYNLSNBCJAPZJHNYJTUNIBC

[collinsezedike]

@s6pa1rta3n-lab Closing. #168 has no assignee. Comment on the issue and wait to be assigned before opening a PR.