fix(journal): tokenize bare dice notation

The tokenizer only recognized dice when the pattern started with a count (3d6), so a bare d20 fell through to the identifier branch and failed as an unknown identifier. Add a dedicated branch for the bare d-form; DICE_RE already accepted it.

src/cli/completions/variable-system.test.ts

@@ -379,6 +379,20 @@ describe("evaluateExpression", () => {
     expect(result.value.value).toBeLessThanOrEqual(23);
   });
 
+  test("evaluates bare dice notation", () => {
+    const result = evaluateExpression("d20", { lookup: () => undefined });
+    expect(result.value.kind).toBe("number");
+    expect(result.value.value).toBeGreaterThanOrEqual(1);
+    expect(result.value.value).toBeLessThanOrEqual(20);
+  });
+
+  test("evaluates bare dice alongside modifiers", () => {
+    const result = evaluateExpression("d6 + 5", { lookup: () => undefined });
+    expect(result.value.kind).toBe("number");
+    expect(result.value.value).toBeGreaterThanOrEqual(6);
+    expect(result.value.value).toBeLessThanOrEqual(11);
+  });
+
   test("throws on division by zero", () => {
     expect(() =>
       evaluateExpression("10 / 0", { lookup: () => undefined }),