feat(validation): improve user-facing schema validation errors

[saquibsaifee]

Description

• Provide a stable, safe presentation of validation failures so callers (UIs/tools) can display actionable messages instead of raw backend error objects.
• Make nested JSON schema failures more useful by preferring the most relevant jsonschema context error when available.
• Normalize XML validation log entries into the same message/path shape used for JSON.

Fixes issue: #827

AI Tool Disclosure

• My contribution does not include any AI-generated content
• My contribution includes AI-generated content, as disclosed below:
  • AI Tools: GTP Codex
  • LLMs and versions: GPT-5.3-Codex
  • Prompts: [Summarize the key prompts or instructions given to the AI tools]

Affirmation

• My code follows the CONTRIBUTING.md guidelines

[read-the-docs-community]

Documentation build overview

📚 CycloneDX Python Library | 🛠️ Build #32727992 | 📁 Comparing 7b5f220 against latest (0daf3f9)

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2 files changed

± genindex.html
± autoapi/cyclonedx/validation/index.html

[codacy-production]

Up to standards ✅

🟢 Issues 0 issues

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