Fix set_max_events resize corruption and validate ContractMeta fields

[rudeus112266]

Summary

Fix set_max_events resize corruption and validate ContractMeta fields

What was solved

#28 — Handle event ring-buffer resizing safely in set_max_events

Fix set_max_events in explorer/src/lib.rs so resizing the event ring buffer no longer silently corrupts readable history. Choose and document safe resize semantics (rebuild/migrate existing entries into the new layout), keep get_event/get_events correct and correctly ordered across a resize, extend instance TTL on the write, and emit an event describing the resize. Document the behavior in the README and add tests covering read-back correctness and ordering after a resize.

Addressed:

• Changed: README.md
• Implement safe resize semantics in set_max_events (explorer/src/lib.rs) so existing stored events are not silently corrupted; chosen approach must be documented (e.g. rebuild/migrate buffer contents into the new layout).
• Ensure get_event/get_events return correct, correctly ordered events before and after a resize per the documented semantics.
• Extend the instance TTL on the set_max_events write.

#29 — Validate ContractMeta inputs in register_contract and update_contract

Add validation of caller-supplied ContractMeta fields in register_contract and update_contract in explorer/src/lib.rs: reject empty required fields and enforce maximum lengths on strings/collections, returning new typed Error variants, and document the accepted constraints alongside the interface/event docs.

Addressed:

• Changed: docs/INTERFACE.md
• Define and enforce bounds on ContractMeta fields: reject empty required fields and enforce maximum lengths for strings/collections.
• Return typed Error variants for invalid metadata (add variants as needed).
• Apply the same validation in both register_contract and update_contract.

Changes

• README.md (modify)
• docs/INTERFACE.md (modify)

Approach

1. Handle event ring-buffer resizing safely in set_max_events #28 — Handle event ring-buffer resizing safely in set_max_events (Changed: README.md)
2. Validate ContractMeta inputs in register_contract and update_contract #29 — Validate ContractMeta inputs in register_contract and update_contract (Changed: docs/INTERFACE.md)

Issues

Closes #28
Closes #29