fix(dql): support IRI-ref at query start (#9667)

**Description**

This PR fixes a regression in DQL lexing where queries starting with an
IRI-ref (names wrapped in `< >`, e.g., `<caseNodeDel_xxx>`) would fail
with an `Unexpected character: U+003C '<'` error.

**Root Cause:**
In v25, the state function `lexIdentifyMutationOrQuery` was introduced
to distinguish between mutations and queries. However, it lacked a case
for the `lsThan` (`<`) character, causing the lexer to fail when a query
block started with an IRI-ref instead of a standard name or keyword.

**Changes:**
- Updated `lexIdentifyMutationOrQuery` in `dql/state.go` to handle the
`lsThan` (`<`) case.
- Ensures the lexer correctly calls `lex.IRIRef` and transitions to
`lexQuery`.

Fixes #9666

**Checklist**

- [x] The PR title follows the [Conventional
Commits](https://www.conventionalcommits.org/en/v1.0.0/#summary) syntax,
leading with `fix:`, `feat:`, `chore:`, `ci:`, etc.
- [x] Code compiles correctly and linting (via trunk) passes locally
- [x] Tests added for new functionality, or regression tests for bug
fixes added as applicable

---------

Co-authored-by: gooohgb <[email protected]>

Author: eileenaaa

dql/dql_test.go

@@ -86,6 +86,11 @@ func TestParseDQL(t *testing.T) {
 				<name> <is> <something-else> .
 			}
 		}`,
+		`{
+			<user-query>(func: uid(0x1)) {
+				name
+			}
+		}`,
 	}
 
 	for _, tc := range testCases {

dql/state.go

@@ -388,6 +388,9 @@ func lexIdentifyMutationOrQuery(l *lex.Lexer) lex.StateFn {
 			// else it is a query
 			l.Emit(itemName)
 			return lexQuery
+		case r == lsThan:
+			l.Backup()
+			return lexQuery
 		case r == '#':
 			return lexComment
 		case r == lex.EOF:

dql/state_test.go

@@ -193,6 +193,24 @@ func TestVariablesDefault(t *testing.T) {
 	}
 }
 
+func TestIRIRefInIdentifyMutationOrQuery(t *testing.T) {
+	input := `{
+		<user-query>(func: uid(0x1)) {
+			name
+		}
+	}`
+	l := lex.Lexer{
+		Input: input,
+	}
+	l.Run(lexTopLevel)
+	it := l.NewIterator()
+	for it.Next() {
+		item := it.Item()
+		require.NotEqual(t, item.Typ, lex.ItemError, "Error: %v", item.String())
+		t.Log(item.String())
+	}
+}
+
 func TestIRIRef(t *testing.T) {
 	input := `
 	query testQuery {