fix(llm): let a model refuse temperature, and say which extractor is installed

Two reports, both about an import that fails without saying why.

#2262 — temperature: 0 sat in the shared request body, so it went out on every
attempt including both retries. Reasoning models (the gpt-5 family) reject any
explicit temperature, and the json_object retry fires on any 400, so the import
spent two doomed requests and could not succeed at all. The parameter is now
dropped once a server has explicitly said it will not take it.

Not as a third link in the chain, though. A gpt-5 rejects max_tokens AND
temperature, the API names one parameter per response, and it may name either
first — a chain of one-shot ifs converges on only one of the two orders. The
retries are a loop over what the server actually said instead: each remedy
applies at most once and they compose. Detection is a phrase, not the bare word,
because dropping temperature costs the deterministic sampling that small local
models depend on, and an unfamiliar wording still falls through to the
json_object retry exactly as before. NuExtract and Ollama are untouched: the
first attempt always carries temperature, and it is the only one they ever see.

#2261 — the bundled extractor is Debian trixie's 24.12.3, roughly eighteen
months behind upstream, and the reporter is right that this is invisible: a
stale extractor, a mistyped KITINERARY_EXTRACTOR_PATH and a genuinely
unsupported provider all look the same from the UI, which is nothing imported
and no reason given. The version now appears in the startup log and in a new
admin-only GET /api/admin/system-info, and LOG_LEVEL=debug passes the
extractor's raw stderr through — the JS ERROR and Invalid-result-type lines the
filter drops are the only evidence that a vendor script is missing or failing.
Capped at 200 lines, and opt-in because those lines can carry document
fragments.

Not bumping the package: the filter the reporter needs first ships in KDE Gear
26.08 and no Debian suite carries it, and sid's 26.04.3 wants KF6 6.22 and Qt6
6.10.2 against trixie's 6.6 and 6.8.2 — a partial upgrade of Qt6, KF6 and libc6
from unstable into the production image, on two architectures, that still would
not fix the reported carrier. It comes for free with the base-image move after
Debian 14.

server/.env.example

@@ -52,6 +52,8 @@ DEMO_MODE=false # Demo mode - resets data hourly
 # OVERPASS_URL= # Custom Overpass endpoint(s) for the map POI "explore" search, comma-separated. When set, REPLACES the bundled public mirrors — point it at an internal/self-hosted Overpass instance when the public ones are unreachable from your network. Non-http(s) entries are ignored. If you don't self-host Overpass but the public mirrors throttle you, setting APP_URL also gives outbound requests a unique User-Agent the mirrors rate-limit less.
 # OVERPASS_TIMEOUT_MS=12000 # Per-endpoint timeout (ms) for Overpass POI requests; slower endpoints are abandoned so a faster mirror wins. Raise it for a slow self-hosted instance. (default: 12000)
 
+# KITINERARY_EXTRACTOR_PATH= # Full path to the kitinerary-extractor binary. Unset, TREK searches /usr/lib/*/libexec/kf6/ and then PATH; the official image pins it. Set it to run a newer extractor than your distribution packages — the version in use is in the startup log and in GET /api/admin/system-info. (default: auto-detected)
+
 # LLM_TIMEOUT_MS=900000 # Ceiling (ms) for one AI-parsing call before it is abandoned. One value for every provider, and the underlying HTTP client is held to it too. Generous by default so heavier parsing work fits without a code change; lower it on a cloud provider to fail fast. (default: 900000)
 
 # UNSPLASH_ACCESS_KEY= # Optional Unsplash Access Key for trip-cover and place-image search. Without one, TREK uses Unsplash's unauthenticated endpoint, which some datacenter/VPS IPs get blocked from (#1449). Get a free key at unsplash.com/developers. Overrides any key set per-admin in Admin > Settings. Can also be configured there instead of here.