jmiba/Zotero-add-items-from-text: Add Items from Text 1.0.14

Custom model selection release. Model fields now accept manually entered IDs for Gemini, OpenAI-compatible endpoints, and Ollama. Refresh Models updates autocomplete suggestions without replacing a custom value. Discovery no longer hides compatible Gemini models or IDs reported by OpenAI-compatible and Ollama endpoints. Documentation explains direct model selection. Adds regression coverage for editable fields, preference persistence, and refresh behavior. Verified with all 13 automated tests, lint, a production build, strict MkDocs validation, and inspection of the packaged XPI.