Open WebUI: add optional OpenTelemetry package install

[irishpadres]

✍️ Description

Open WebUI users who enable OpenTelemetry tracing/metrics currently have to manually reinstall the OTEL Python packages after every update, because update_script runs uv tool install --force, which fully recreates the tool's virtual environment and silently drops any package that isn't one of Open WebUI's own declared dependencies.

This adds an install-time prompt to optionally install the OpenTelemetry instrumentation packages (API, SDK, OTLP exporters, and instrumentation for FastAPI/aiohttp/httpx/SQLAlchemy/requests/logging/redis/system-metrics) via uv tool install --with <pkg>. update_script then detects whatever opentelemetry-* packages are currently installed in the live venv before reinstalling (uv pip list --format freeze | grep '^opentelemetry-') and re-supplies them as --with args, so they survive every future update automatically. This detection is based on live venv state rather than a persisted flag, so it also retroactively fixes containers that already had these packages added by hand before this change existed — no need to have used the prompt in the first place.

Users still need to configure the relevant OTEL_* variables in /root/.env themselves — this only handles package installation, not enabling/configuring OpenTelemetry itself.

Note: this only preserves OpenTelemetry packages specifically; any other manually uv pip install-ed package in this venv would still be dropped on update. Scoped to OpenTelemetry only, matching the actual problem being fixed here.

Tested: fresh install with the prompt answered "yes" (packages import correctly), update on a freshly-installed container with OTEL present (survives --force reinstall), update on an existing container that had OTEL packages added manually before this change existed with no prior marker (detected and preserved), and update on a container with no OTEL packages (no behavior change).

🔗 Related Issue

Fixes #

✅ Prerequisites (X in brackets)

• Self-review completed – Code follows project standards.
• Tested thoroughly – Changes work as expected.
• No security risks – No hardcoded secrets, unnecessary privilege escalations, or permission issues.

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🛠️ Type of Change (X in brackets)

• 🐞 Bug fix – Resolves an issue without breaking functionality.
• ✨ New feature – Adds new, non-breaking functionality.
• 💥 Breaking change – Alters existing functionality in a way that may require updates.
• 🆕 New script – A fully functional and tested script or script set.
• 🌍 Website update – Changes to script metadata (PocketBase/website data).
• 🔧 Refactoring / Code Cleanup – Improves readability or maintainability without changing functionality.
• 📝 Documentation update – Changes to README, AppName.md, CONTRIBUTING.md, or other docs.