Use SvelteKit param matchers for bilingual URL routing (e.g. /fitness/stats
and /fitness/statistik). Add centralized i18n module with translation
dictionary, language detection from URL, and path conversion utilities.
Translate all UI text across pages, components, and navigation.
- 5-tab layout (Profile, History, Workout, Exercises, Measure) with shared header nav
- Workout system: template CRUD, active workout on /fitness/workout/active with localStorage persistence, pause/resume timer, rest timer, RPE input
- Shared workout singleton (getWorkout) so active workout state is accessible across all fitness routes
- Floating workout FAB indicator on all /fitness routes when workout is active
- AddActionButton component for button-based FABs (measure + template creation)
- Profile page with workouts-per-week bar chart and weight line chart with SMA trend line + ±1σ confidence band
- Exercise detail with history, charts, and records tabs using static exercise data
- Session history with grouped-by-month list, session detail with stats/PRs
- Body measurements with latest values, body part display, add form
- Card styling matching rosary/prayer route patterns (accent-dark, nord5 light, box-shadow, hover lift)
- FitnessChart: fix SSR hang by moving Chart.register to client-side, remove redundant $effect
- Exercise API: use static in-repo data instead of empty MongoDB collection
- Workout finish: include exercise name for WorkoutSession model validation
