test(rust): cover Azure table URI separators (#3837)

## Root cause

The former listing-database table URI builder used OS-native
`Path::join` for object-store URIs. On Windows this inserted backslashes
into `az://` table paths, so `table_names` found slash-delimited objects
while `open_table` addressed a different key. The production path now
builds URI paths with forward slashes after the equivalent S3 report was
fixed in #2575, but #1072 remained open without Azure-specific
regression coverage.

## Fix

- Add Azure URI regression assertions at the Rust table URI construction
boundary.
- Cover connection bases both with and without a trailing slash,
matching the behavior reported in #1072.
- Verify the resulting table URI always uses forward slashes on every
platform.

## Validation

- `cargo fmt --all -- --check`
- `cargo test --quiet -p lancedb --lib
database::listing::tests::test_table_uri`
- `cargo check --quiet --features remote --tests --examples`
- `cargo clippy --quiet --features remote --tests --examples`
- `cargo test --quiet --features remote --tests` (866 passed, 1 ignored)

Fixes #1072

<!-- lance-gatekeeper-fix:v1 agent=7d385255a072ed89ddc3ff4d08f82218
generation=1 -->

Co-authored-by: Gatefixer <313497061+lancedb-gatefixer[bot]@users.noreply.github.com>

rust/lancedb/src/database/listing.rs

@@ -2342,7 +2342,7 @@ mod tests {
 
     #[tokio::test]
     async fn test_table_uri() {
-        let (_tempdir, db) = setup_database().await;
+        let (_tempdir, mut db) = setup_database().await;
 
         let mut pb = PathBuf::new();
         pb.push(db.uri.clone());
@@ -2351,6 +2351,18 @@ mod tests {
         let expected = pb.to_str().unwrap();
         let uri = db.table_uri("test").ok().unwrap();
         assert_eq!(uri, expected);
+
+        // URI paths always use forward slashes, even on Windows. Using
+        // `Path::join` here used to produce `az://container/prefix\\test.lance`,
+        // which Azure treated as a different object from the table returned by
+        // `table_names` (https://github.com/lancedb/lancedb/issues/1072).
+        for base_uri in ["az://container/prefix", "az://container/prefix/"] {
+            db.uri = base_uri.to_string();
+            assert_eq!(
+                db.table_uri("test").unwrap(),
+                "az://container/prefix/test.lance"
+            );
+        }
     }
 
     /// Regression: connecting via a URL-style URI (which goes through