feat: add mentorship assignments and peer review enhancements

- Create `mentorship_assignments` table with relevant fields and indexes.
- Add `peer_review_settings` table for lesson-specific peer review configurations.
- Enhance `peer_reviews` and `course_submissions` tables with additional fields for instructor reviews and final scores.
- Implement My Notes page to display user annotations with delete functionality.
- Create Lesson Annotations component for managing notes with editing and deletion capabilities.
- Develop Mentor Panel component to display mentor and mentee information.
- Add Course Mentorships page for assigning mentors to students with modal for selection.

Co-authored-by: Copilot <copilot@github.com>

services/lms-service/migrations/20260428000002_mentorship_assignments.sql

@@ -0,0 +1,15 @@
+CREATE TABLE IF NOT EXISTS mentorship_assignments (
+    id              UUID        PRIMARY KEY DEFAULT gen_random_uuid(),
+    organization_id UUID        NOT NULL,
+    course_id       UUID        NOT NULL,
+    mentor_id       UUID        NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+    student_id      UUID        NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+    assigned_by     UUID        NOT NULL,   -- instructor que realizó la asignación
+    notes           TEXT,                   -- notas internas del instructor
+    created_at      TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    UNIQUE (course_id, mentor_id, student_id)
+);
+
+CREATE INDEX IF NOT EXISTS idx_mentorship_course       ON mentorship_assignments (course_id, organization_id);
+CREATE INDEX IF NOT EXISTS idx_mentorship_mentor       ON mentorship_assignments (mentor_id, organization_id);
+CREATE INDEX IF NOT EXISTS idx_mentorship_student      ON mentorship_assignments (student_id, organization_id);