Add lesson progress tracking

- Toggle lesson completion via server action (LessonProgress table)
- "Отметить как пройденный" button on lesson page, turns accent when done
- Course sidebar: progress bar, checkmarks on completed lessons, X/Y counter per module
- Dashboard: progress bar on each course card with completion percentage

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

src/components/student/course-sidebar.tsx

@@ -21,10 +21,22 @@ interface Course {
   modules: Module[];
 }
 
-export function CourseSidebar({ course }: { course: Course }) {
+export function CourseSidebar({
+  course,
+  completedLessonIds = new Set(),
+}: {
+  course: Course;
+  completedLessonIds?: Set<string>;
+}) {
   const pathname = usePathname();
   const [open, setOpen] = useState(true);
 
+  const totalLessons = course.modules.reduce((s, m) => s + m.lessons.length, 0);
+  const completedCount = course.modules
+    .flatMap((m) => m.lessons)
+    .filter((l) => completedLessonIds.has(l.id)).length;
+  const progressPct = totalLessons > 0 ? Math.round((completedCount / totalLessons) * 100) : 0;
+
   return (
     <>
       {/* Mobile toggle */}
@@ -45,54 +57,101 @@ export function CourseSidebar({ course }: { course: Course }) {
           top: "53px",
         }}
       >
-        {/* Course title */}
+        {/* Course title + progress */}
         <div className="px-4 py-4" style={{ borderBottom: "2px solid var(--border)" }}>
           <Link
             href={`/courses/${course.slug}`}
-            className="font-bold text-sm leading-snug block"
+            className="font-bold text-sm leading-snug block mb-1"
             style={{ color: "var(--foreground)" }}
           >
             {course.title}
           </Link>
           <Link
             href="/dashboard"
-            className="text-xs mt-1 block underline"
+            className="text-xs block underline mb-3"
             style={{ color: "var(--muted-foreground)" }}
           >
             ← Все курсы
           </Link>
+
+          {totalLessons > 0 && (
+            <div>
+              <div className="flex items-center justify-between mb-1">
+                <span className="text-xs" style={{ color: "var(--muted-foreground)" }}>
+                  {completedCount} из {totalLessons} уроков
+                </span>
+                <span className="text-xs font-bold" style={{ color: "var(--foreground)" }}>
+                  {progressPct}%
+                </span>
+              </div>
+              <div
+                className="h-1.5 w-full"
+                style={{ background: "var(--border)" }}
+              >
+                <div
+                  className="h-full transition-all duration-300"
+                  style={{
+                    width: `${progressPct}%`,
+                    background: progressPct === 100 ? "var(--foreground)" : "var(--accent)",
+                    border: progressPct > 0 ? "1px solid var(--foreground)" : "none",
+                  }}
+                />
+              </div>
+            </div>
+          )}
         </div>
 
         {/* Modules and lessons */}
         <nav className="flex-1 py-2">
-          {course.modules.map((mod) => (
-            <div key={mod.id}>
-              <p
-                className="px-4 py-2 text-xs font-bold uppercase tracking-widest"
-                style={{ color: "var(--muted-foreground)" }}
-              >
-                {mod.title}
-              </p>
-              {mod.lessons.map((lesson) => {
-                const active = pathname.includes(lesson.id);
-                return (
-                  <Link
-                    key={lesson.id}
-                    href={`/courses/${course.slug}/lessons/${lesson.id}`}
-                    className="block px-4 py-2 text-sm leading-snug border-l-2 transition-colors"
-                    style={{
-                      borderLeftColor: active ? "var(--foreground)" : "transparent",
-                      backgroundColor: active ? "var(--color-highlight)" : "transparent",
-                      color: active ? "var(--foreground)" : "var(--foreground)",
-                      fontWeight: active ? 600 : 400,
-                    }}
+          {course.modules.map((mod) => {
+            const modCompleted = mod.lessons.filter((l) => completedLessonIds.has(l.id)).length;
+            return (
+              <div key={mod.id}>
+                <div className="flex items-center justify-between px-4 py-2">
+                  <p
+                    className="text-xs font-bold uppercase tracking-widest"
+                    style={{ color: "var(--muted-foreground)" }}
                   >
-                    {lesson.title}
-                  </Link>
-                );
-              })}
-            </div>
-          ))}
+                    {mod.title}
+                  </p>
+                  {mod.lessons.length > 0 && (
+                    <span className="text-xs" style={{ color: "var(--muted-foreground)" }}>
+                      {modCompleted}/{mod.lessons.length}
+                    </span>
+                  )}
+                </div>
+                {mod.lessons.map((lesson) => {
+                  const active = pathname.includes(lesson.id);
+                  const done = completedLessonIds.has(lesson.id);
+                  return (
+                    <Link
+                      key={lesson.id}
+                      href={`/courses/${course.slug}/lessons/${lesson.id}`}
+                      className="flex items-center gap-2 px-4 py-2 text-sm leading-snug border-l-2 transition-colors"
+                      style={{
+                        borderLeftColor: active ? "var(--foreground)" : "transparent",
+                        backgroundColor: active ? "var(--color-highlight)" : "transparent",
+                        fontWeight: active ? 600 : 400,
+                        color: done && !active ? "var(--muted-foreground)" : "var(--foreground)",
+                      }}
+                    >
+                      <span
+                        className="shrink-0 w-4 h-4 flex items-center justify-center text-xs"
+                        style={{
+                          border: `1.5px solid ${done ? "var(--foreground)" : "var(--border)"}`,
+                          background: done ? "var(--foreground)" : "transparent",
+                          color: "var(--background)",
+                        }}
+                      >
+                        {done && "✓"}
+                      </span>
+                      <span className="flex-1 leading-snug">{lesson.title}</span>
+                    </Link>
+                  );
+                })}
+              </div>
+            );
+          })}
         </nav>
       </aside>
     </>