feat: implement QuestionBank CRUD with pagination and template query

- Add pagination support to findAll (page, limit query params)
- Add findByTemplateId method to service
- Add GET /by-template/:templateId endpoint to controller
- Service already includes CRUD for QuestionBank and QuestionBankItem

server/src/assessment/migrations/add_question_banks.sql

@@ -0,0 +1,45 @@
+-- Migration: Create Question Banks Tables
+-- Run this SQL to create the question_banks and question_bank_items tables
+
+-- Create QuestionBanks table
+CREATE TABLE IF NOT EXISTS question_banks (
+    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    tenant_id VARCHAR(255),
+    template_id UUID,
+    name VARCHAR(255) NOT NULL,
+    description TEXT,
+    status VARCHAR(50) DEFAULT 'DRAFT',
+    created_by VARCHAR(255),
+    reviewed_by VARCHAR(255),
+    reviewed_at TIMESTAMP,
+    review_comment TEXT,
+    created_at TIMESTAMP DEFAULT NOW(),
+    updated_at TIMESTAMP DEFAULT NOW(),
+    CONSTRAINT fk_template FOREIGN KEY (template_id) REFERENCES assessment_templates(id) ON DELETE SET NULL
+);
+
+-- Create QuestionBankItems table
+CREATE TABLE IF NOT EXISTS question_bank_items (
+    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    bank_id UUID NOT NULL,
+    question_text TEXT NOT NULL,
+    question_type VARCHAR(50) DEFAULT 'SHORT_ANSWER',
+    options JSONB,
+    correct_answer TEXT,
+    key_points JSONB NOT NULL,
+    difficulty VARCHAR(50) DEFAULT 'STANDARD',
+    dimension VARCHAR(50) DEFAULT 'PROMPT',
+    basis TEXT,
+    created_by VARCHAR(255),
+    created_at TIMESTAMP DEFAULT NOW(),
+    updated_at TIMESTAMP DEFAULT NOW(),
+    CONSTRAINT fk_bank FOREIGN KEY (bank_id) REFERENCES question_banks(id) ON DELETE CASCADE
+);
+
+-- Create indexes for performance
+CREATE INDEX IF NOT EXISTS idx_question_banks_tenant_id ON question_banks(tenant_id);
+CREATE INDEX IF NOT EXISTS idx_question_banks_status ON question_banks(status);
+CREATE INDEX IF NOT EXISTS idx_question_banks_created_by ON question_banks(created_by);
+CREATE INDEX IF NOT EXISTS idx_question_bank_items_bank_id ON question_bank_items(bank_id);
+CREATE INDEX IF NOT EXISTS idx_question_bank_items_difficulty ON question_bank_items(difficulty);
+CREATE INDEX IF NOT EXISTS idx_question_bank_items_dimension ON question_bank_items(dimension);