docs: correct data workflows, SQL and operations (#4534)

This PR is part of the documentation revamp. Once the full set of PRs is
merged, we’ll publish the combined site to staging for review before
updating docs.lancedb.com.

The curation, SQL and operations pages contain outdated claims and
examples that do not reliably work as written.

This corrects those pages against the reviewed SDK and local server
evidence, including prepared statements, background jobs, cleanup and
monitoring. Integration guides are grouped with their examples in #4533.

Function and Secret-object documentation stays unpublished until its
release. The two Function pages are listed in `.mintignore` and left out
of the navigation, and the sections about them on other pages are MDX
comments.

Stacked on #4533. Each MDX file has one PR owner. Rebase onto main after
#4533 is squash-merged.

Local assembly, Mint validation and link checks pass, and the assembled
site shows no Function or Secret-object content. A local release
rehearsal that uncomments the drafts and restores the navigation also
passes. Hold publication until this PR and lancedb/sophon#8688 are on
`main`.

docs/web/sql/ddl/function.mdx

@@ -6,17 +6,22 @@ icon: function
 keywords: ["create function", "drop function", "show functions", "sql", "udf"]
 ---
 
-<Badge color="red">Enterprise</Badge> [SQL runs on a deployment.](/sql)
+<Badge color="red">Enterprise</Badge> [SQL runs in LanceDB Enterprise.](/sql)
 
 ## CREATE FUNCTION {#create}
 
 ```sql
-CREATE FUNCTION f(x BIGINT) RETURNS BIGINT
+CREATE FUNCTION f(x int64) RETURNS int64
 LANGUAGE python
 AS 'def f(x): return x * 2'
 WITH (pip = 'numpy==1.26.4', python_version = '3.11')
 ```
 
+Parameter and result types are Arrow type names, not SQL ones: `int64`,
+`float64`, `utf8`, `bool`, `date32`, and lists such as `list<float32>` or
+`fixed_size_list<float32, 768>`. `BIGINT` is refused. A parameter accepts nulls
+unless it is declared `NOT NULL`.
+
 The body is Python source. Its dependencies are declared with it and are part
 of the **immutable function version** -- changing one produces a new version
 rather than altering the registered one, so a column filled by an earlier
@@ -27,7 +32,7 @@ version is unaffected.
 | `pip` | pip requirements for the worker environment |
 | `conda` | conda packages instead of pip |
 | `conda_channels` | channels in priority order; requires `conda` |
-| `python_version` | worker Python version, defaulting to yours |
+| `python_version` | worker Python version; `3.12` when omitted, whatever Python you send the statement from |
 | `gpu` | `'true'` when every execution needs a GPU |
 
 **Errors and limits**