feat!: rename branch merge to cherry_pick

BREAKING CHANGE: Remote branch promotion is `cherry_pick` /
`branches.cherry_pick` / `branches.cherryPick`. The HTTP path is
`POST /v1/table/{id}/branches/cherry_pick/`. Success status is
`cherryPicked`. Diff JSON uses `errors` (`ApplyError`) instead of
`mergeable`/`blockers`/`ready`; a cherry-pick that does not apply
returns `failed`. Pair with the matching Phalanx contract.
`merge_insert` and `Table.merge` are unchanged.

python/src/table.rs

@@ -1885,7 +1885,7 @@ impl Branches {
     }
 
     #[pyo3(signature = (from_branch, dry_run=false))]
-    pub fn merge(
+    pub fn cherry_pick(
         self_: PyRef<'_, Self>,
         from_branch: String,
         dry_run: bool,
@@ -1893,7 +1893,7 @@ impl Branches {
         let inner = self_.inner.clone();
         future_into_py(self_.py(), async move {
             let result = inner
-                .merge_branch(&from_branch, dry_run)
+                .cherry_pick(&from_branch, dry_run)
                 .await
                 .infer_error()?;
             Python::attach(|py| struct_to_wire_py(py, &result))