Add language info strings to Markdown fences

[wenjiehs]

Summary

• Add language info strings to previously unlabeled Markdown code fences in docs and supporting Markdown.
• Use text for transcripts, formulas, CLI output, ASCII diagrams, and prose examples; use yaml where the fenced content is YAML.
• Fix one nested transcript in src/content/docs/ai-ml/ai-copilot/user-stories.md by using a four-backtick outer fence so embedded yaml and bash examples remain valid Markdown.

Doc Change Report

Source issue: TKE-60

Modified scope:

• Markdown-only syntax-label updates across src/content/docs/**, top-level contributing docs, tmp/tke-skill-k8s-mcp-integration.md, and related supporting Markdown found by the health-check scope.
• No cookbook Python, navigation, config, API semantics, commands, resource guidance, pricing, versions, or production strategy changed.

canonical_doc_path: N/A - site-wide Markdown code fence hygiene, not a single operation document.
operation_id: tke.docs.markdown-fence-info-strings

Fact sources:

• Multica issue TKE-60 description: Health Check TKE-59 reported unlabeled Markdown fences and requested obvious language labels (bash, yaml, json, python, text) without command-semantic changes.
• Repository Markdown content in the modified files. Official Tencent Cloud product/API sources are not applicable because this PR does not change cloud behavior, API parameters, or operational guidance.

Static Compile:

• Fence-aware validator: unlabeled_openings=0, unclosed_fences=0
• npm run build passed
• node --test test/navigation.test.mjs test/cookbooks.test.mjs test/create-cluster-autoupgrade.test.mjs passed
• python3 -B -m py_compile over cookbook/**/*.py passed
• git diff --check passed
• mkdocs build --strict skipped: no mkdocs.yml or mkdocs.yaml exists in this repository

Dry Run Compile:

• Confirmed changes are code fence info-string edits only, plus one Markdown fence-length correction for nested sample content.
• No executable command content, parameters, API names, cleanup steps, or validation steps were changed.

Live Verify:

• Not required. This change is documentation rendering/syntax hygiene only and does not create, delete, or manage Tencent Cloud/TKE resources.

Remaining human confirmation:

• None for this scoped Markdown hygiene change.

[github-actions]

✅ 构建成功！PR 合并后将自动部署。