Implement storage TTL bumping and archival handling for stream entries in streampay-stream

[greatest0fallt1me]

Description

Long-running streams may span days or weeks, so persistent stream entries and instance storage must have their TTLs extended to avoid archival mid-stream. This addresses the org's "durable long-running jobs / multi-day stream windows" concern at the contract layer.

Requirements and Context

• Bump persistent entry TTL (env.storage().persistent().extend_ttl(...)) for a stream on every read/write in its money paths.
• Bump instance TTL (env.storage().instance().extend_ttl(...)) for admin/count keys.
• Define and document threshold/extend-to constants tuned for multi-day/multi-week streams.
• Handle restore semantics so a stream survives the entire start_time..end_time window plus a buffer.
• Must be secure, tested, and documented.
• Should be efficient and easy to review.

Suggested Execution

1. Fork the repo and create a branch

   git checkout -b feature/storage-ttl-archival

2. Implement changes
   • contracts/contracts/streampay-stream/src/storage.rs (centralized TTL bump helpers + constants)
   • contracts/contracts/streampay-stream/src/lib.rs (call bumps in read/write paths)
   • contracts/contracts/streampay-stream/src/test.rs (advance ledger sequence, assert TTL extended)
3. Test and commit
   • cd contracts && cargo test -p streampay-stream ttl
   • Cover edge cases (long window near max TTL, repeated bumps)
   • Include test output and notes in the PR

Example commit message

feat: extend storage TTL to survive long stream windows

Acceptance Criteria

• Stream persistent entries have TTL extended on every money-path access
• Instance storage TTL is extended for admin/count keys
• TTL thresholds are named constants and documented
• cargo test advances ledger and asserts entries remain live

Guidelines

• .rs files under contracts/contracts/streampay-stream/src/; tests via cargo test; NatSpec-style /// docs; minimum 95% test coverage; tune TTL for multi-week streams
• Clear documentation and inline comments
• Timeframe: 96 hours

[Lacastar2000]

@Lacastar2000 has applied to work on this issue as part of the Stellar Wave Program's 5th wave.

Hello. Please assign this to me

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Congratulations, @Lacastar2000! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on June 2, 2026.

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This issue has been completed by @Lacastar2000 as part of the Stellar Wave Program's 5th Wave 🥳

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