feat: return a cleanup job from drop_view (#4262)

Dropping a view unbinds its name and leaves the definition dataset to a
server-side cleanup job, so the two are separate events a caller may
want to wait on.

`drop_view_async` returns that job — the same shape
`drop_materialized_view_async` and `drop_function_async` already use: a
`202` carries the job id, a `200` (nothing was bound to the name) yields
an already-finished job with no id, and any other success status is an
error rather than a silent no-op.

## `drop_view` waits

`drop_view` now awaits the job before returning, so a caller who does
not want to think about cleanup gets the stronger guarantee: when it
returns, the definition really is deleted.

That is deliberately **different** from `drop_materialized_view` and
`drop_function`, which return as soon as the name is unbound and
document that content may still be deleting. The view API is the newer
one, and waiting is the semantic worth having; the other two are left
alone rather than changing behaviour already released.

## Surfaces

`Database` trait, the remote client, `Connection`, and the Python and
Node bindings — matching where `drop_materialized_view_async` is already
exposed.

Four client tests cover the accepted case reporting its job id, the
nothing-bound case reporting a finished job, a `202` without a usable
`job_id`, and an unexpected success status.

docs/src/js/classes/Connection.md

@@ -557,9 +557,10 @@ on the returned job to know when cleanup has finished.
 abstract dropView(name, namespacePath?): Promise<void>
 ```
 
-Drop the view named `name`.
+Drop the view named `name` and wait for its definition to be deleted.
 
-The tables it reads are untouched: a view holds no rows of its own.
+The tables it reads are untouched: a view holds no rows of its own. Use
+[dropViewAsync](Connection.md#dropviewasync) to retain the cleanup job instead of waiting on it.
 
 #### Parameters
 
@@ -573,6 +574,30 @@ The tables it reads are untouched: a view holds no rows of its own.
 
 ***
 
+### dropViewAsync()
+
+```ts
+abstract dropViewAsync(name, namespacePath?): Promise<Job>
+```
+
+Start dropping the view named `name` and return the job deleting its
+definition, without waiting for completion.
+
+The name is free before this resolves. When nothing was bound to it, the
+returned job is already finished and has no id.
+
+#### Parameters
+
+* **name**: `string`
+
+* **namespacePath?**: `string`[]
+
+#### Returns
+
+`Promise`&lt;[`Job`](Job.md)&gt;
+
+***
+
 ### isOpen()
 
 ```ts