Phase 4: grade comments with frequency-ranked suggestions

- progress comment_templates (tone + use_count) and grade_comments tables;
  setGrade now accepts comments list; templates created/bumped automatically;
  GET /api/v1/comment-templates?q= returns suggestions ranked by frequency
- admin group page: per-grade ✎ dialog (score + editable comment rows with
  tone, datalist suggestions), chips under each score, data-comments JSON attr
- student lab page: score + colored tone chips
- fixed damaged button/attributes from earlier manual template surgery

services/progress-service/src/main/resources/db/migration/V6__grade_comments.sql

@@ -0,0 +1,19 @@
+-- Grade comments: reusable templates (frequency-ranked) + per-grade comments.
+
+CREATE TABLE comment_templates (
+    id         uuid PRIMARY KEY DEFAULT uuidv7(),
+    text       text NOT NULL UNIQUE,
+    tone       varchar(8) NOT NULL DEFAULT 'neutral',   -- positive | neutral | negative
+    use_count  integer NOT NULL DEFAULT 1
+);
+
+CREATE TABLE grade_comments (
+    id          uuid PRIMARY KEY DEFAULT uuidv7(),
+    student_id  uuid    NOT NULL,
+    lab_id      uuid    NOT NULL,
+    text        text    NOT NULL,
+    tone        varchar(8) NOT NULL DEFAULT 'neutral',
+    created_at  timestamptz NOT NULL DEFAULT now()
+);
+
+CREATE INDEX grade_comments_grade_idx ON grade_comments (student_id, lab_id);