docs: add interactive Soroban smart contract parameter cheat sheet (Closes #1367)

[camesenin]

Description

This pull request addresses issue #1367 by publishing a comprehensive, developer-oriented Soroban smart contract parameter cheat sheet in \docs/SOROBAN_PARAMETER_CHEATSHEET.md\ and linking it from both \contracts/CONTRIBUTING.md\ and the root \README.md.

Changes Included

• Comprehensive Cheat Sheet (\docs/SOROBAN_PARAMETER_CHEATSHEET.md):
  • Quick Function & Storage Matrix: High-level mapping of function names, required authorizations, storage tiers (Instance, Persistent, Temporary), storage key formats, and emitted events across contracts.
  • Contract-by-Contract Breakdown:
    • \contracts/campaign: Signatures, argument types, explicit instance vs persistent storage keys, error code dictionary (codes 100-126), and event schemas.
    • \contracts/rewards: Escrow operations, balance tracking, and distribution invariants.
    • \contracts/badges: Non-transferable (Soulbound) NFT semantics and storage keys.
    • \contracts/voting\ & \contracts/nullifiers: Ballot structures, quorum requirements, and nullifier hash validation for double-voting defense.
  • Soroban Host Functions & Rent TTL Reference: Complete guidelines for ledger-based storage management (\TTL_THRESHOLD\ and \TTL_EXTEND_TO) and host function usage.
• Index Links: Cross-referenced in \contracts/CONTRIBUTING.md\ and root \README.md\ for immediate discoverability.

Acceptance Criteria

• Host functions, argument types, and storage keys are exhaustively documented
• Clear authorization boundaries and error dictionaries provided
• Linked from the documentation index and contributor guides

Closes #1367

[camesenin]

Hi @Gbangbolaoluwagbemiga @joelpeace48-cell, this PR is ready for review with all tests passing. Could you please assign me to this issue on Drips Wave (@camesenin) so that it is properly tracked for Wave 9 before merging? Thank you!