fix: remove ignore_directories from REPO.bazel for Bazel 7 compat (#47)

`ignore_directories` was introduced in Bazel 8 and causes a parse error
when this module is consumed by Bazel 7 users. Move the ignored dirs to
`.bazelignore` which is supported across all Bazel versions.

Fixes #40

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: longlho

.bazelignore

@@ -0,0 +1,7 @@
+# Examples are separate workspaces
+examples
+# Bazel convenience symlinks
+bazel-bin
+bazel-out
+bazel-rules_formatjs
+bazel-testlogs

REPO.bazel

@@ -5,13 +5,3 @@ repo(
         "//:package_metadata",
     ],
 )
-
-ignore_directories([
-    # Examples are separate workspaces
-    "examples",
-    # Bazel convenience symlinks
-    "bazel-bin",
-    "bazel-out",
-    "bazel-rules_formatjs",
-    "bazel-testlogs",
-])