perf(contract): define TTL budgets for streams, supply, and admin state

[arisu6804]

Problem

Unbounded stream state or redundant TTL bumps can exceed transaction budgets and make active records expire unexpectedly.

Objective

Deliver a production-quality improvement to persistent storage and TTL management that creates measurable value for correctness, security, reliability, performance, or maintainability.

Implementation scope

• Define TTL policy per record type; avoid repeated bumps in one invocation; add bounded cleanup for terminal streams.

Acceptance criteria

• Active streams remain available within documented policy; cleanup cannot remove live commitments; operations fit the storage budget.

Required validation

• Instrumentation, expiry, cleanup, and budget tests on active and terminal records.
• Existing tests and CI remain passing.
• Add regression coverage for the original failure mode.
• Do not weaken, delete, or skip unrelated tests to obtain a green build.

PR quality bar

• Keep the PR focused and explain design tradeoffs, compatibility impact, and test evidence.
• Avoid typo-only, documentation-only, cosmetic-only, or unrelated refactor submissions.

Out of scope

• Broad rewrites not required by the acceptance criteria.
• Changes to unrelated services, contracts, or user flows.