Add new skills for backend patterns, coding standards, continuous learning, and NestJS best practices

- Introduced backend patterns skill with guidelines on API design, database optimization, and server-side best practices.
- Added coding standards skill outlining universal coding principles for TypeScript, NestJS, and Node.js development.
- Implemented continuous learning skill to automatically extract reusable patterns from Cursor sessions.
- Created NestJS best practices skill detailing architecture patterns, dependency injection, error handling, and security measures.
- Included various rules and templates for NestJS best practices to ensure production-ready applications.

.cursor/hooks/memory-persistence/session-start.sh

@@ -0,0 +1,24 @@
+#!/bin/bash
+# SessionStart Hook - Load previous context on new session
+#
+# Configured in .cursor/hooks.json:
+#   sessionStart -> node .cursor/scripts/hooks/session-start.js
+# This shell version is a fallback for environments without Node.
+
+ROOT="$(git rev-parse --show-toplevel 2>/dev/null || pwd)"
+SESSIONS_DIR="${ROOT}/.cursor/sessions"
+LEARNED_DIR="${ROOT}/.agents/skills/learned"
+
+recent_sessions=$(find "$SESSIONS_DIR" -name "*.tmp" -mtime -7 2>/dev/null | wc -l | tr -d ' ')
+
+if [ "$recent_sessions" -gt 0 ]; then
+  latest=$(ls -t "$SESSIONS_DIR"/*.tmp 2>/dev/null | head -1)
+  echo "[SessionStart] Found $recent_sessions recent session(s)" >&2
+  echo "[SessionStart] Latest: $latest" >&2
+fi
+
+learned_count=$(find "$LEARNED_DIR" -name "*.md" 2>/dev/null | wc -l | tr -d ' ')
+
+if [ "$learned_count" -gt 0 ]; then
+  echo "[SessionStart] $learned_count learned skill(s) available in $LEARNED_DIR" >&2
+fi