v2.2.23 - Resilient API Error Handling

This release adds retry logic and sanitised error messages when the LLM API fails.

Problem:
When the OpenAI API returned a transient error (e.g. Cloudflare 520), the raw HTML error page was dumped directly into the chat, producing a wall of unreadable markup for the user.

Changes:

• HTML error detection: sanitizeApiError() detects HTML responses (Cloudflare, nginx, etc.) and extracts the <title> for a concise one-line message
• Automatic retries: Transient errors (429, 500, 502, 503, 504, 520-522, 524) now retry up to 2 times with exponential back-off (3s, 6s)
• User status updates: During retries the chat shows "AI service temporarily unavailable — retrying (1/2)…" so users know what's happening
• Friendly catch-all errors: Timeout and connection-refused errors now show human-readable messages instead of raw Error: <message>
• Error text capping: Non-HTML errors longer than 400 chars are truncated to avoid flooding the UI

Result: Users now see a short, actionable message like "The AI service returned an error (api.openai.com | 520: Web server is returning an unknown error). This is usually a temporary issue — please try again in a moment." — and in most cases the retry succeeds transparently.