ci: lint .github markdown and fix the violations it exposed (#12290)

.github/agents/issue-triage.md

@@ -199,7 +199,7 @@ You MUST structure your response using this EXACT format. Do NOT include anythin
 
 ### For Check Logic Bug
 
-```
+```markdown
 ### AI Assessment [Experimental]: Check Logic Bug
 
 **Component**: {component from issue template}
@@ -297,7 +297,7 @@ Write tests FIRST (TDD). The skills contain all testing conventions and patterns
 
 ### For Bug (non-check)
 
-```
+```markdown
 ### AI Assessment [Experimental]: Bug
 
 **Component**: {CLI/SDK | API | UI | Dashboard | MCP Server | Other}
@@ -378,7 +378,7 @@ Write tests FIRST (TDD). The skills contain all testing conventions and patterns
 
 ### For Already Fixed
 
-```
+```markdown
 ### AI Assessment [Experimental]: Already Fixed
 
 **Component**: {component}
@@ -401,7 +401,7 @@ Upgrade to the latest version. Close the issue as resolved.
 
 ### For Feature Request
 
-```
+```markdown
 ### AI Assessment [Experimental]: Feature Request
 
 **Component**: {component}
@@ -419,7 +419,7 @@ Upgrade to the latest version. Close the issue as resolved.
 
 ### For Not a Bug
 
-```
+```markdown
 ### AI Assessment [Experimental]: Not a Bug
 
 **Component**: {component}
@@ -440,7 +440,7 @@ Upgrade to the latest version. Close the issue as resolved.
 
 ### For Needs More Information
 
-```
+```markdown
 ### AI Assessment [Experimental]: Needs More Information
 
 **Component**: {component or "Unknown"}

.github/scripts/slack-messages/README.md

@@ -8,11 +8,11 @@ These JSON templates are used with the `slackapi/slack-github-action` using the
 
 ### Available Templates
 
-**Container Releases**
+#### Container Releases
 - `container-release-started.json`: Simple one-line notification when container push starts
 - `container-release-completed.json`: Simple one-line notification when container release completes
 
-**Deployments**
+#### Deployments
 - `deployment-started.json`: Deployment start notification with Block Kit formatting
 - `deployment-completed.json`: Deployment completion notification (updates the start message)
 
@@ -416,17 +416,17 @@ For deployments that start with one message and update it with the final status:
 ### Container Release (Simple One-Line)
 
 **Start message:**
-```
+```text
 API container release 4.5.0 push started... View run
 ```
 
 **Completion message (success):**
-```
+```text
 [✓] API container release 4.5.0 push completed successfully! View run
 ```
 
 **Completion message (failure):**
-```
+```text
 [✗] API container release 4.5.0 push failed View run
 ```
 

.github/workflows/markdown-lint.yml

@@ -55,6 +55,10 @@ jobs:
         # Pin must match .pre-commit-config.yaml so prek and CI behave identically.
         # pnpm dlx doesn't accept --ignore-scripts as a flag; the env var
         # disables postinstall scripts on transitives the same way.
+        #
+        # Files come from `git ls-files` because markdownlint doesn't traverse
+        # dot-directories, so `.github/**/*.md` went unlinted.
+        # `.markdownlintignore` still applies to the listed paths.
         env:
           pnpm_config_ignore_scripts: 'true'
-        run: pnpm dlx markdownlint-cli@0.45.0 '**/*.md'
+        run: git ls-files -z '*.md' | xargs -0 -r pnpm dlx markdownlint-cli@0.45.0 --