fix(i18n): strip code fences from translations, translate nav labels

[01programs]

Summary

Three critical fixes for translation quality:

1. MDX code fence wrapping (63% of files broken)

The LLM was wrapping translations in ```mdx code blocks, which broke Mintlify rendering.

Fixes:

• Updated prompt to explicitly forbid code fences
• Added post-processing to strip fences if they appear
• Added validation that output starts with --- frontmatter

2. Navigation labels staying in English

Sidebar group/tab names (e.g., "Search", "Files", "Schedules") were not being translated.

Fixes:

• Updated update-docs-config.ts to translate labels via OpenAI
• Added translation cache to avoid redundant API calls

3. OpenAPI descriptions not translated (NEW)

API field descriptions (the gray text in API reference pages) come from OpenAPI spec files and were not being translated.

Fixes:

• Added translate-openapi.ts: Programmatically extracts only translatable fields (description, summary, title) and batch translates them
• Preserves all technical fields exactly (property names, types, enums, URLs)
• Updated workflow: New translate-openapi job runs in parallel with MDX translation
• Updated update-docs-config.ts: Adds language-specific OpenAPI paths to API tabs

Architecture

                    ┌──────────────────────────────────────┐
                    │              setup                    │
                    └────────────────┬─────────────────────┘
                                     │
                    ┌────────────────┼────────────────┐
                    ▼                ▼                ▼
           ┌───────────────┐ ┌───────────────┐ ┌───────────────┐
           │ translate-    │ │ translate-    │ │ translate-    │
           │ openapi       │ │ catchup (MDX) │ │ incremental   │
           └───────────────┘ └───────────────┘ └───────────────┘
                    │                │                │
                    └────────────────┴────────────────┘
                                     │
                    ┌────────────────▼─────────────────────┐
                    │              deploy                   │
                    └──────────────────────────────────────┘

Test plan

• Merge PR
• Trigger workflow manually (or wait for next push to main)
• Verify MDX pages render correctly (no raw MDX code)
• Verify sidebar labels are translated
• Verify API field descriptions (gray text) are translated
• Verify API property names, types stay in English