perf(onchain): replace locked Map with per-token instance storage

[ifygreg01-best]

Switch TotalLocked from a single Map<Address, i128> cell to a typed contracttype enum key — TotalLocked::Token(Address) — so each token's locked amount occupies its own instance-storage cell.

Previously, every decrement_locked call (claim, disburse, revoke, cancel_package, refund) deserialised the entire map, mutated one entry, and re-serialised the whole map — an O(N) ratchet that grew with the number of distinct tokens. Each create_package and batch_create_packages also performed the same full read/write inline.

Changes:

• Add TotalLocked contracttype enum (Token(Address) variant)
• Add get_locked / set_locked private helpers (single-cell O(1) read/write)
• Remove KEY_TOTAL_LOCKED constant (no longer needed)
• Update all 7 sites: create_package, batch_create_packages, decrement_locked, get_total_locked, withdraw_surplus
• batch_create_packages retains its single read-before/write-after pattern, preserving atomic batch accounting and eliminating the reentrancy window where intermediate locked values were visible
• Regenerate test snapshots to reflect new storage key layout

All 106 tests pass unchanged (aid_escrow_tests, gas_profiling, integration, batch, boundary, e2e, events, versioning, invariants).

Summary

Testing

# example
npm test

Screenshots

Checklist

• Tests added or updated for new/changed behavior
• Existing tests pass
• No secrets, keys, or seed phrases committed
• Follows the coding conventions in the relevant service README
• PR is focused on a single concern
  closes Replace optimistic Map writes on KEY_TOTAL_LOCKED with try_mutate semantics #224

[kilodesodiq-arch]

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