Add backend/frontend scaffolding with Oracle ADB wallet config

- Backend: Spring Boot 3 + WebFlux, JWT auth, Oracle ADB wallet,
  8 controllers/services/repositories (Auth~Tag), DTOs, exception handling
- Frontend: Next.js 15, TypeScript, Tailwind CSS, AuthContext,
  7 pages (dashboard, knowledge, chat, study, todos, habits, login)
- DB: V1 migration with 12 tables including VECTOR(1024) + HNSW index
- Ops: PM2 ecosystem config, deploy.sh, start-backend.sh
- CLAUDE.md: DB credentials replaced with env var references

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

start-backend.sh

@@ -0,0 +1,9 @@
+#!/bin/bash
+set -a
+source /home/opc/sundol/.env
+set +a
+
+JAVA_HOME=${JAVA_HOME:-/usr/lib/jvm/java-21}
+export JAVA_HOME
+
+exec $JAVA_HOME/bin/java -jar /home/opc/sundol/sundol-backend/target/sundol-backend-0.0.1-SNAPSHOT.jar