agents(rules): use comma-separated string for globs frontmatter (#4275)

Jetski unmarshals the `globs` rule frontmatter field into a string, so
YAML sequence values (`!!seq`) in `github_actions_workflows.md` and
`lockfiles.md` failed to parse when loading customizations.

Convert `globs` in `github_actions_workflows.md` and `lockfiles.md` to
quoted, comma-separated strings, quote `*.bzl` in `bzl.md`, and
document the string requirement in `rule-creator/SKILL.md`.

.agents/rules/bzl.md

diff --git a/.agents/rules/bzl.md b/.agents/rules/bzl.md
index 10aca72..9812520 100644
--- a/.agents/rules/bzl.md
+++ b/.agents/rules/bzl.md
@@ -1,7 +1,7 @@
 ---
 trigger: glob
 description: Starlark / Bazel .bzl file coding style rules
-globs: *.bzl
+globs: "*.bzl"
 ---
 
 # Starlark Rules

.agents/rules/github_actions_workflows.md

diff --git a/.agents/rules/github_actions_workflows.md b/.agents/rules/github_actions_workflows.md
index f417ed1..b5b0d6e 100644
--- a/.agents/rules/github_actions_workflows.md
+++ b/.agents/rules/github_actions_workflows.md
@@ -1,7 +1,7 @@
 ---
 name: github-actions-workflows
 trigger: glob
-globs: [".github/workflows/**"]
+globs: ".github/workflows/**"
 ---
 
 # GitHub Actions Workflows Rule

.agents/rules/lockfiles.md

diff --git a/.agents/rules/lockfiles.md b/.agents/rules/lockfiles.md
index edc455e..d0f6d67 100644
--- a/.agents/rules/lockfiles.md
+++ b/.agents/rules/lockfiles.md
@@ -1,13 +1,8 @@
 ---
 trigger: glob
 description: Rules for updating uv.lock and requirements.txt files
-globs:
-  - "*requirements*.txt"
-  - "*requirements*.in"
-  - "uv.lock"
-  - "pyproject.toml"
-  - "*constraints*.txt"
-  - "*gazelle_python*.yaml"
+globs: "*requirements*.txt,*requirements*.in,uv.lock,pyproject.toml,\
+  *constraints*.txt,*gazelle_python*.yaml"
 ---
 
 # Lockfile & Dependency Rules

.agents/skills/rule-creator/SKILL.md

diff --git a/.agents/skills/rule-creator/SKILL.md b/.agents/skills/rule-creator/SKILL.md
index 4a6201f..e36d092 100644
--- a/.agents/skills/rule-creator/SKILL.md
+++ b/.agents/skills/rule-creator/SKILL.md
@@ -36,7 +36,9 @@
     relevant. Prefer `model_decision` for conceptual, architectural, or
     cross-cutting rules (e.g., `pr.md`, `rules_python.md`).
 *   `glob`: The rule activates when matching files (`globs:`) are accessed.
-    Use for syntax/formatting rules tied to specific file types.
+    Use for syntax/formatting rules tied to specific file types. `globs` must
+    be a quoted, comma-separated string (e.g., `globs: "*.bzl,BUILD.bazel"`),
+    never a YAML list/sequence.
 
 ### Domain Separation
 *   Keep language and tool rule files (`starlark.md`, `bzl.md`, `python.md`,