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/routes/logging.py

@@ -0,0 +1,177 @@
+"""Workout logging routes for inline set tracking.
+
+Handles creating, editing, and deleting individual set logs.
+All responses are HTMX partials that update in place.
+"""
+
+from datetime import date
+
+import structlog
+from fastapi import APIRouter, Depends, Request
+from fastapi.responses import HTMLResponse
+from sqlmodel import Session
+
+from app.database import get_db_session
+from app.models.user import User
+from app.services.log_service import LogService
+from app.services.workout_session_service import WorkoutSessionService
+from app.utils.auth import get_current_admin_user, get_active_profile_id
+
+logger = structlog.get_logger(__name__)
+
+router = APIRouter(prefix="/log", tags=["logging"])
+
+
+@router.post("", response_class=HTMLResponse)
+async def log_set(
+    request: Request,
+    session: Session = Depends(get_db_session),
+    admin: User = Depends(get_current_admin_user),
+):
+    """Log a single set for an exercise.
+
+    Creates the workout session if it doesn't exist yet (auto-create).
+    Returns the updated log entries partial for this exercise.
+
+    Args:
+        request: The incoming HTTP request.
+        session: Database session.
+        admin: The authenticated admin user.
+
+    Returns:
+        Rendered log entries partial for this exercise.
+    """
+    form = await request.form()
+    exercise_id = int(form.get("exercise_id", 0))
+    workout_day_id = int(form.get("workout_day_id", 0))
+    set_number = int(form.get("set_number", 1))
+    reps = int(form.get("reps", 0))
+    weight = form.get("weight", "")
+    felt_easy = form.get("felt_easy") == "on"
+
+    active_profile_id = get_active_profile_id(request)
+    if not active_profile_id:
+        templates = request.app.state.templates
+        return templates.TemplateResponse("partials/flash_message.html", {
+            "request": request,
+            "flash_error": "No profile selected. Switch profiles first.",
+        })
+
+    # Get or create today's session
+    ws_service = WorkoutSessionService(session)
+    ws = ws_service.get_or_create_session(
+        user_id=active_profile_id,
+        workout_day_id=workout_day_id,
+        session_date=date.today(),
+    )
+
+    # Create the log entry
+    log_service = LogService(session)
+    log_service.create_log(
+        session_id=ws.id,
+        exercise_id=exercise_id,
+        set_number=set_number,
+        reps_completed=reps,
+        weight_used=weight,
+        felt_easy=felt_easy,
+    )
+
+    # Return updated logs for this exercise
+    logs = log_service.list_logs_for_exercise(ws.id, exercise_id)
+    next_set = len(logs) + 1
+
+    templates = request.app.state.templates
+    return templates.TemplateResponse("partials/log_entry.html", {
+        "request": request,
+        "logs": logs,
+        "exercise_id": exercise_id,
+        "workout_day_id": workout_day_id,
+        "next_set": next_set,
+        "session_id": ws.id,
+    })
+
+
+@router.post("/{log_id}/edit", response_class=HTMLResponse)
+async def edit_log(
+    log_id: int,
+    request: Request,
+    session: Session = Depends(get_db_session),
+    admin: User = Depends(get_current_admin_user),
+):
+    """Edit an existing log entry.
+
+    Args:
+        log_id: The log entry ID.
+        request: The incoming HTTP request.
+        session: Database session.
+        admin: The authenticated admin user.
+
+    Returns:
+        Rendered updated log entry partial.
+    """
+    form = await request.form()
+    log_service = LogService(session)
+
+    log_service.update_log(
+        log_id,
+        reps_completed=int(form.get("reps", 0)),
+        weight_used=form.get("weight", ""),
+        felt_easy=form.get("felt_easy") == "on",
+        notes=form.get("notes"),
+    )
+
+    log = log_service.get_log_by_id(log_id)
+    logs = log_service.list_logs_for_exercise(log.session_id, log.exercise_id)
+    next_set = len(logs) + 1
+
+    templates = request.app.state.templates
+    return templates.TemplateResponse("partials/log_entry.html", {
+        "request": request,
+        "logs": logs,
+        "exercise_id": log.exercise_id,
+        "workout_day_id": 0,
+        "next_set": next_set,
+        "session_id": log.session_id,
+    })
+
+
+@router.post("/{log_id}/delete", response_class=HTMLResponse)
+async def delete_log(
+    log_id: int,
+    request: Request,
+    session: Session = Depends(get_db_session),
+    admin: User = Depends(get_current_admin_user),
+):
+    """Delete a log entry.
+
+    Args:
+        log_id: The log entry ID.
+        request: The incoming HTTP request.
+        session: Database session.
+        admin: The authenticated admin user.
+
+    Returns:
+        Rendered updated log entries partial.
+    """
+    log_service = LogService(session)
+    log = log_service.get_log_by_id(log_id)
+
+    if log:
+        exercise_id = log.exercise_id
+        session_id = log.session_id
+        log_service.delete_log(log_id)
+
+        logs = log_service.list_logs_for_exercise(session_id, exercise_id)
+        next_set = len(logs) + 1
+
+        templates = request.app.state.templates
+        return templates.TemplateResponse("partials/log_entry.html", {
+            "request": request,
+            "logs": logs,
+            "exercise_id": exercise_id,
+            "workout_day_id": 0,
+            "next_set": next_set,
+            "session_id": session_id,
+        })
+
+    return HTMLResponse("")