feat: Refactor workout functionality into blueprint

- Moved workout-related routes (create/delete/edit workouts, topsets, tags, start dates, show workout) from `app.py` into a new blueprint at `routes/workout.py`.
- Integrated workout view model logic from `features/workout.py` directly into `routes/workout.py` helper function `_get_workout_view_model`.
- Removed `features/workout.py` and the corresponding class instantiation in `db.py`.
- Registered the new `workout_bp` blueprint in `app.py`.
- Removed the original workout route definitions from `app.py`.
- Updated `url_for` calls in relevant templates (`workout.html`, `person_overview.html`, `partials/workout_tags.html`, `partials/topset.html`, `partials/start_date.html`, `partials/new_set_form.html`, `notes.html`, `calendar.html`) to reference the new blueprint endpoints (e.g., `workout.create_workout`).
- Updated `templates/changelog/changelog.html` to document this refactoring.

templates/notes.html

@@ -50,7 +50,7 @@
                 {% for workout_note in workout_notes %}
                 <tr class="border-b transition-colors hover:bg-muted/50 data-[state=selected]:bg-muted">
                     <td class="p-4 align-middle [&amp;:has([role=checkbox])]:pr-0 cursor-pointer"
-                        hx-get="{{ url_for('show_workout', person_id=person_id, workout_id=workout_note.workout_id) }}"
+                        hx-get="{{ url_for('workout.show_workout', person_id=person_id, workout_id=workout_note.workout_id) }}"
                         hx-push-url="true" hx-target="#container">
                         <div class="flex flex-row items-center justify-center">
                             <button
@@ -96,7 +96,7 @@
 {% block add_workout_button %}
 <button
     class="fixed z-90 bottom-10 right-8 bg-blue-600 w-20 h-20 rounded-full drop-shadow-lg flex justify-center items-center text-white text-4xl hover:bg-blue-700 hover:drop-shadow-2xl hover:animate-bounce duration-300"
-    hx-post="{{ url_for('create_workout', person_id=person_id) }}" hx-push-url="true" hx-target="#container">
+    hx-post="{{ url_for('workout.create_workout', person_id=person_id) }}" hx-push-url="true" hx-target="#container">
     <svg viewBox="0 0 20 20" enable-background="new 0 0 20 20" class="w-6 h-6 inline-block">
         <path fill="#FFFFFF" d="M16,10c0,0.553-0.048,1-0.601,1H11v4.399C11,15.951,10.553,16,10,16c-0.553,0-1-0.049-1-0.601V11H4.601
                                 C4.049,11,4,10.553,4,10c0-0.553,0.049-1,0.601-1H9V4.601C9,4.048,9.447,4,10,4c0.553,0,1,0.048,1,0.601V9h4.399