refactor: modernize SDK and overhaul access, pause, and mint flow

[cak3ninja]

A modernization of the SWEAT token contract that overhauls its security model, removes legacy minting paths, and prepares the contract for an upgrade migration. End-user behavior is preserved; operational and governance behavior changes significantly.

New capabilities

• Role-based access control. Privileged operations are now governed by named roles (Super Admin, Oracle, DenylistManager, PauseManager, UnpauseManager) managed through standard grant/revoke calls. Replaces the previous ad-hoc oracle list.
• Account denylist. A new DenylistManager role can flag any account as restricted. Restricted accounts can no longer send, receive, or burn tokens, and cannot deregister from storage while restricted.
• Group pause / unpause. Operations are split into two pause groups — minting (the oracle deferred-mint flow) and token (transfers and burns) — each independently pausable and unpausable by the corresponding role.
• Mandatory holding account. The deferred-mint flow now requires a configured holding contract: user payouts are routed there for later claim, while the oracle fee goes to the calling oracle. The holding account is set at initialization and locked thereafter.
• Upgrade migration. A first-class migration entry point lets the contract be upgraded in place from the previous deployed version, with the old wasm preserved for reference.

Removed / hardened behavior

• Direct mint methods removed. Tokens can only enter circulation through the deferred-batch oracle flow; there is no longer an ad-hoc admin mint.
• Legacy non-deferred recording removed. The older "record" path and its oracle-management methods are gone; oracles now operate exclusively through the deferred batch path and the ACL.
• Failure rollback for step accounting. If a batch record fails on callback, the global step-since-TGE counter is reverted so that the issuance formula stays accurate.
• Holding-account identity locked. The configured holding account cannot be changed after initialization, removing a class of misconfiguration risk.

Quality & operations

• Modernized NEAR SDK. Contract is updated to the current NEAR SDK and a current Rust toolchain, with the contract-standards library vendored locally so future SDK bumps are reproducible.
• Comprehensive integration test suite. New end-to-end test coverage for access control, pausing, denylist restrictions, migration, deferred minting, payout splits, and callback-attack resistance.
• Refreshed documentation and tooling. README rewritten to describe the new mint/claim model, role management, deployment, and build workflow; build, lint, test, and coverage commands consolidated behind a single make interface.
• Published contract artifacts. Built wasm and ABI for both the token and the holding-contract stub are now checked in as release artifacts, alongside the previous wasm for upgrade reference.

Net product impact

The token now has a clearly defined permission model, a single auditable path for issuance, an account-level compliance lever (denylist), independent kill-switches for minting vs. transfers, and a supported upgrade path — all without changing the end-user-facing token economics or the NEP-141/145/148 surface.