feat!: rename branch merge to cherry_pick (#3986)

This PR is a **breaking** rename of #3686.

merge reads like git merge w/ three-way, replay history, combine two
lines of work. That is not this API.

This call takes one additive change on a branch and lands it on main.
New column, including a blob column. Main's existing columns are not
rewritten. If it cannot land, you get `status="failed"` and
`diff.errors`, not a merge conflict to resolve.

Cherry-pick is terminology that aligns more with that.

```python
table = db.open_table("images")
table.branches.create("exp")
exp = table.branches.checkout("exp")

exp.add_columns({"tag": "cast('draft' as string)"})

diff = table.branches.diff("exp")
preview = table.branches.cherry_pick("exp", dry_run=True)
result = table.branches.cherry_pick("exp")

if result["status"] == "cherryPicked":
    print("landed at", result["mainVersionAfter"])
elif result["status"] == "failed":
    print(result["diff"]["errors"])
```

### Behavior

- Remote / Enterprise only. Local still NotSupported.
- HTTP 409 is not an exception. It is Ok with status="failed" and
diff.errors (CherryPickError).
- Unknown error / status codes still parse as Unknown.
- Requests are not retried. 409 is final and carries the body.
- Endpoint is POST /v1/table/{id}/branches/cherry_pick/.
- merge_insert and Table.merge are unchanged.

### Testing
- `cargo test -p lancedb --features remote diff_branch`
- `cargo test -p lancedb --features remote cherry_pick`
- `pytest python/python/tests/test_remote_db.py -k cherry_pick`
- node `remote.test.ts` diffs / cherry-picks path

docs/src/js/interfaces/BranchDiff.md

@@ -50,6 +50,14 @@ changedColumns: BranchColumnChange[];
 
 ***
 
+### errors
+
+```ts
+errors: CherryPickError[];
+```
+
+***
+
 ### fromBranch
 
 ```ts
@@ -66,22 +74,6 @@ mainVersion: number;
 
 ***
 
-### mergeBlockers
-
-```ts
-mergeBlockers: MergeBlocker[];
-```
-
-***
-
-### mergeable
-
-```ts
-mergeable: boolean;
-```
-
-***
-
 ### parentVersion
 
 ```ts

docs/src/js/interfaces/CherryPickError.md

@@ -2,11 +2,11 @@
 
 ***
 
-[@lancedb/lancedb](../globals.md) / MergeBlocker
+[@lancedb/lancedb](../globals.md) / CherryPickError
 
-# Interface: MergeBlocker
+# Interface: CherryPickError
 
-A reason why a branch cannot currently be merged.
+A reason why a cherry-pick cannot currently land.
 
 ## Properties
 

docs/src/js/interfaces/CherryPickPreview.md

@@ -0,0 +1,17 @@
+[**@lancedb/lancedb**](../README.md) • **Docs**
+
+***
+
+[@lancedb/lancedb](../globals.md) / CherryPickPreview
+
+# Interface: CherryPickPreview
+
+Changes that would be, or were, promoted by a cherry-pick.
+
+## Properties
+
+### promotedColumns
+
+```ts
+promotedColumns: string[];
+```

docs/src/js/interfaces/CherryPickResult.md

@@ -2,11 +2,11 @@
 
 ***
 
-[@lancedb/lancedb](../globals.md) / MergeBranchResult
+[@lancedb/lancedb](../globals.md) / CherryPickResult
 
-# Interface: MergeBranchResult
+# Interface: CherryPickResult
 
-Result of previewing or attempting a branch merge.
+Result of previewing or attempting a cherry-pick.
 
 ## Properties
 
@@ -29,7 +29,7 @@ optional mainVersionAfter: number;
 ### preview
 
 ```ts
-preview: MergePreview;
+preview: CherryPickPreview;
 ```
 
 ***
@@ -38,9 +38,9 @@ preview: MergePreview;
 
 ```ts
 status:
+  | "failed"
   | "unknown"
-  | "rejected"
   | "ready"
   | "notImplemented"
-  | "merged";
+  | "cherryPicked";
 ```

docs/src/js/interfaces/MergePreview.md

@@ -1,17 +0,0 @@
-[**@lancedb/lancedb**](../README.md) • **Docs**
-
-***
-
-[@lancedb/lancedb](../globals.md) / MergePreview
-
-# Interface: MergePreview
-
-Changes that would be, or were, promoted by a branch merge.
-
-## Properties
-
-### promotedColumns
-
-```ts
-promotedColumns: string[];
-```