feat: workout-suggester, weather-aware workouts from a local Gemma

Go + Templ + HTMX app that checks the weather (Open-Meteo, MET Norway
fallback), scores run/ride/walk with plain rules, and has a local
open-weight model (Gemma 4 E2B via any OpenAI-compatible server) write
the plan. Routes are loops from your door (BRouter) plus signposted
OpenStreetMap routes (Overpass), with GPX export.

internal/weather/testdata/geocode.json

@@ -0,0 +1 @@
+{"results":[{"id":2797656,"name":"Ghent","latitude":51.05,"longitude":3.71667,"elevation":10.0,"feature_code":"PPL","country_code":"BE","admin1_id":3337388,"admin2_id":2789733,"admin3_id":2797655,"admin4_id":2797657,"timezone":"Europe/Brussels","population":265086,"postcodes":["9000"],"country_id":2802361,"country":"Belgium","admin1":"Flanders","admin2":"East Flanders","admin3":"Arrondissement of Ghent","admin4":"Gent"}],"generationtime_ms":0.7789135}