Add Unicode wiki paths and label validation

[humandebri]

Summary

• Preserve Unicode VFS paths for generated pages, alongside source-language titles, section labels, and body content.
• Validate LLM-generated section labels at the generation boundary and reject empty or multi-line labels.
• Update the WikiBrowser deploy script to use wrangler deploy --minify, matching the production deployment requirement from the PR 29 rollout.
• Adjust the vfs_runtime index migration so source_run_sessions can be added safely to existing schemas.

Testing

• Ran pnpm test and pnpm typecheck in workers/wiki-generator to cover label validation and Unicode path regression cases.
• Ran WikiBrowser path, dashboard, and security checks to verify the minified deploy script and Unicode URL handling.
• Ran vfs_runtime migration tests and clippy to verify existing index schema upgrades remain safe.