🐛 Fix Alpine.js SyntaxError and backlink visibility issues

- Fix SyntaxError in viewer.js line 2868 (.bind(this) issue in setTimeout)
- Resolve Alpine.js 'Can't find variable' errors (documentViewer, goBack, etc.)
- Fix backlink rendering and persistence during temporary highlights
- Add backlink protection and restoration mechanism in highlightAndScrollToText
- Implement Note Management System with hierarchical notebooks
- Add note highlights and memos functionality
- Update cache version to force browser refresh (v=2025012641)
- Add comprehensive logging for debugging backlink issues

backend/migrations/011_create_note_highlights_and_notes.sql

@@ -0,0 +1,48 @@
+-- 노트용 하이라이트 테이블 생성
+CREATE TABLE note_highlights (
+    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    note_id UUID NOT NULL REFERENCES notes_documents(id) ON DELETE CASCADE,
+    start_offset INTEGER NOT NULL,
+    end_offset INTEGER NOT NULL,
+    selected_text TEXT NOT NULL,
+    highlight_color VARCHAR(50) NOT NULL DEFAULT '#FFFF00',
+    highlight_type VARCHAR(50) NOT NULL DEFAULT 'highlight',
+    created_at TIMESTAMP WITH TIME ZONE DEFAULT NOW(),
+    updated_at TIMESTAMP WITH TIME ZONE DEFAULT NOW(),
+    created_by VARCHAR(100) NOT NULL
+);
+
+-- 노트용 메모 테이블 생성
+CREATE TABLE note_notes (
+    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    note_id UUID NOT NULL REFERENCES notes_documents(id) ON DELETE CASCADE,
+    highlight_id UUID REFERENCES note_highlights(id) ON DELETE CASCADE,
+    content TEXT NOT NULL,
+    created_at TIMESTAMP WITH TIME ZONE DEFAULT NOW(),
+    updated_at TIMESTAMP WITH TIME ZONE DEFAULT NOW(),
+    created_by VARCHAR(100) NOT NULL
+);
+
+-- 인덱스 생성
+CREATE INDEX ix_note_highlights_note_id ON note_highlights (note_id);
+CREATE INDEX ix_note_highlights_created_by ON note_highlights (created_by);
+CREATE INDEX ix_note_notes_note_id ON note_notes (note_id);
+CREATE INDEX ix_note_notes_highlight_id ON note_notes (highlight_id);
+CREATE INDEX ix_note_notes_created_by ON note_notes (created_by);
+
+-- updated_at 자동 업데이트 트리거
+CREATE OR REPLACE FUNCTION update_updated_at_column()
+RETURNS TRIGGER AS $$
+BEGIN
+    NEW.updated_at = NOW();
+    RETURN NEW;
+END;
+$$ language 'plpgsql';
+
+CREATE TRIGGER update_note_highlights_updated_at 
+    BEFORE UPDATE ON note_highlights 
+    FOR EACH ROW EXECUTE FUNCTION update_updated_at_column();
+
+CREATE TRIGGER update_note_notes_updated_at 
+    BEFORE UPDATE ON note_notes 
+    FOR EACH ROW EXECUTE FUNCTION update_updated_at_column();