v0.2.3

fix: sanitize Langfuse base URL to avoid "invalid uri character"

ureq rejects a base URL containing quotes, whitespace, or a trailing
newline with "invalid uri character", and a trailing slash caused a
silent redirect failure. Users commonly quote the value in their config
file (LANGFUSE_BASE_URL="https://..."), and the config parser preserved
the quotes verbatim.

- config: strip one layer of matching surrounding quotes from values
- main: trim whitespace/quotes and a trailing slash from the host

Bumps version to 0.2.3.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>