Add lib.rs entrypoint deprecation marker and DeprecatedCall event

[greatest0fallt1me]

Description

The contract has accumulated multiple legacy entrypoints (e.g. early dispute filing variants) that should be phased out. Introduce a #[deprecated] annotation pattern plus a DeprecatedCall(entrypoint: Symbol) event so callers are signalled at runtime and indexers can chart usage decay.

Requirements and Context

• Helper emit_deprecated(env, entrypoint) in events.rs
• Apply to at least two known legacy entrypoints
• Document deprecation policy in docs/
• 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/deprecated-entrypoint-events

2. Implement changes
   • contracts/predictify-hybrid/src/lib.rs
   • contracts/predictify-hybrid/src/events.rs
3. Test and commit
   • cargo test -p predictify-hybrid deprecated_call
   • Cover edge cases
   • Include test output and notes in the PR

Example commit message

feat: mark legacy entrypoints with deprecation event

Acceptance Criteria

• At least two entrypoints emit the deprecation event
• Doc section explains policy
• Behaviour of deprecated entrypoints unchanged

Guidelines

• Clear documentation and inline comments
• Real Soroban SDK idioms in any new helper code
• Timeframe: 96 hours

[goodness-cpu]

@goodness-cpu has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

Hello Maintainer, I can fix this issue.

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