fix(i18n): replace hardcoded title strings in KnowledgeUpload.vue (#1410)

[mrveiss]

Summary

• Replace 3 hardcoded English title attributes in KnowledgeUpload.vue with $t() calls
• Add clearAllTitle, previewContentTitle, removeFileTitle keys to en.json

Test Plan

• npm run build passes
• No remaining hardcoded title="..." in KnowledgeUpload.vue

Closes #1410

[github-actions]

⚠️ SSOT Configuration Compliance: Violations Found

Metric	Count
Total Violations	371
SSOT Violations (high priority)	286
Other Violations	85

⚠️ 286 values have SSOT config equivalents!

These should be replaced with SSOT config imports:

Python:

from src.config.ssot_config import config
# Use: config.vm.main, config.port.backend, config.backend_url

TypeScript:

import config from '@/config/ssot-config'
// Use: config.vm.main, config.port.backend, config.backendUrl

📖 See SSOT_CONFIG_GUIDE.md for documentation.