[jdjioe5-cpu]

Summary

Closes #2796.

This PR addresses the panic in stellar contract extend where a transaction result metadata with a single operation carrying exactly one LedgerEntryChange passed previous non-empty guards but panicked at cmd/soroban-cli/src/commands/contract/extend.rs:306 with index out of bounds: the len is 1 but the index is 1 during the tuple matching match (&changes[0], &changes[1]).

Changes

1. Replaces raw 2-element index access on changes with iterator-based parse_changes pattern matching
   estore.rs.
2. Searches for Updated or Created ledger entries while safely tracking State entry references without out-of-bounds indexing.
3. Gracefully returns Error::LedgerEntryNotFound when expected changes are absent or invalid.
4. Adds regression unit tests covering:
   • Single-change updated entry avoiding index panic ( est_parse_changes_single_change_updated_avoids_panic)
   • Empty changes returning LedgerEntryNotFound ( est_parse_changes_empty_returns_not_found)
   • Single-change created entry ( est_parse_changes_single_change_created)
   • Two-change sequence with state followed by updated ( est_parse_changes_state_then_updated)