Local deletion backports

Original crates.io yrs 0.23.5 package SHA-256: 197c2b4b298f35c3ba4d549884ac872a961112095b29f173ab45e3d5cf609018.

Only src/transaction.rs differs from the published Rust source:

• Move the deletion scan outside the initial item-split guard so a range beginning at a garbage-collected block still deletes later live blocks. Adapted from upstream PR 614, commit 97095f2e27e4045002b656cec6347e9f9a989c89.
• Store an unapplied deletion tail beginning at the known client state, rather than the original range start; this matches current upstream apply_delete and preserves deletion when missing inserts arrive later.

• Retain complete deletion ranges for clients whose first insert has not arrived yet, matching the upstream missing-client branch.

Garbage collection remains enabled. Wire format, client IDs, undo policy, and sandbox limits are unchanged. Regressions live in native/crdt/tests/rule_delta_convergence.rs, native/crdt/tests/delete_tail_review.rs, and the server core native-rule fixture tests.

The registry package omits its license text; LICENSE is copied from the exact upstream VCS commit 3996e91df00acdb67334695944bc43f60627103f recorded in .cargo_vcs_info.json. Original attribution is retained.