[codex] Fix AI code block rendering fallback

[DeepFal]

Summary

• wrap the Streamdown code highlighter with language normalization and fallback handling
• map generic config fences (conf, cfg, config) to ini
• render unsupported/text fences as plain text tokens instead of blank code blocks

Why

AI assistant responses can include rsyslog-style config snippets such as *.* action(...). When the fence language is generic or unsupported, the highlighter can fail and Streamdown may render the code body incorrectly or blank.

Validation

• node --test --import tsx components/ai/streamdownCodeHighlighter.test.ts
• npm run lint
• npm test
• npm run build

[binaricat]

@codex review

[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. Nice work!

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