feat: add Phase 4 Logging & Tracking — inline set logging, history views

Add workout logging so users can track sets, reps, weight, and a
"felt easy?" toggle inline from the workout day view via HTMX.
Sessions auto-create on first log. History page shows past sessions
with detailed per-exercise breakdowns.

New services: WorkoutSessionService, LogService
New routes: POST /log, /log/{id}/edit, /log/{id}/delete, GET /history, /history/{id}
New templates: log_form, log_entry, session_card, log_history, session_detail
Modified: exercise_card (inline logging), nav (History link), workouts route (session context)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/templates/partials/exercise_card.html

@@ -24,5 +24,18 @@
         <p>{{ exercise.form_cues }}</p>
     </details>
 
-    <!-- Phase 4 adds: inline logging form here -->
+    <!-- Inline logging (Phase 4) -->
+    {% if active_profile %}
+    <div id="logs-exercise-{{ exercise.id }}">
+        {% if existing_logs and existing_logs[exercise.id] %}
+            {% set logs = existing_logs[exercise.id] %}
+            {% set exercise_id = exercise.id %}
+            {% set next_set = logs|length + 1 %}
+            {% include "partials/log_entry.html" %}
+        {% else %}
+            {% set next_set = 1 %}
+            {% include "partials/log_form.html" %}
+        {% endif %}
+    </div>
+    {% endif %}
 </article>