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.

.agents/skills/continuous-learning/SKILL.md

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+---
+name: continuous-learning
+description: Automatically extract reusable patterns from Cursor sessions and save them as learned skills for future use.
+---
+
+# Continuous Learning Skill
+
+Automatically evaluates Cursor sessions on end to extract reusable patterns that can be saved as learned skills.
+
+## How It Works
+
+This skill runs as a **sessionEnd hook** at the end of each session:
+
+1. **Session Evaluation**: Checks if session has enough messages (default: 10+)
+2. **Pattern Detection**: Identifies extractable patterns from the session
+3. **Skill Extraction**: Saves useful patterns to `.agents/skills/learned/`
+
+## Configuration
+
+Edit `config.json` to customize:
+
+```json
+{
+  "min_session_length": 10,
+  "extraction_threshold": "medium",
+  "auto_approve": false,
+  "learned_skills_path": ".agents/skills/learned/",
+  "patterns_to_detect": [
+    "error_resolution",
+    "user_corrections",
+    "workarounds",
+    "debugging_techniques",
+    "project_specific"
+  ],
+  "ignore_patterns": [
+    "simple_typos",
+    "one_time_fixes",
+    "external_api_issues"
+  ]
+}
+```
+
+## Pattern Types
+
+| Pattern | Description |
+|---------|-------------|
+| `error_resolution` | How specific errors were resolved |
+| `user_corrections` | Patterns from user corrections |
+| `workarounds` | Solutions to framework/library quirks |
+| `debugging_techniques` | Effective debugging approaches |
+| `project_specific` | Project-specific conventions |
+
+## Hook Setup
+
+Already wired in `.cursor/hooks.json` as a `sessionEnd` command:
+
+```json
+{
+  "version": 1,
+  "hooks": {
+    "sessionEnd": [
+      {
+        "command": "node .cursor/scripts/hooks/evaluate-session.js"
+      }
+    ]
+  }
+}
+```
+
+## Why Stop Hook?
+
+- **Lightweight**: Runs once at session end
+- **Non-blocking**: Doesn't add latency to every message
+- **Complete context**: Has access to full session transcript
+
+## Related
+
+- [The Longform Guide](https://x.com/affaanmustafa/status/2014040193557471352) - Section on continuous learning
+- `/learn` command - Manual pattern extraction mid-session

.agents/skills/continuous-learning/config.json

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+{
+  "min_session_length": 10,
+  "extraction_threshold": "medium",
+  "auto_approve": false,
+  "learned_skills_path": ".agents/skills/learned/",
+  "patterns_to_detect": [
+    "error_resolution",
+    "user_corrections",
+    "workarounds",
+    "debugging_techniques",
+    "project_specific"
+  ],
+  "ignore_patterns": [
+    "simple_typos",
+    "one_time_fixes",
+    "external_api_issues"
+  ]
+}

.agents/skills/continuous-learning/evaluate-session.sh

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+#!/bin/bash
+# Continuous Learning - Session Evaluator
+# Runs on sessionEnd to extract reusable patterns from Cursor sessions
+#
+# Configured in .cursor/hooks.json:
+#   sessionEnd -> node .cursor/scripts/hooks/evaluate-session.js
+# This shell version is a fallback.
+#
+# Extracted skills saved to: .agents/skills/learned/
+
+set -e
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+ROOT="$(git rev-parse --show-toplevel 2>/dev/null || pwd)"
+CONFIG_FILE="$SCRIPT_DIR/config.json"
+LEARNED_SKILLS_PATH="${ROOT}/.agents/skills/learned"
+MIN_SESSION_LENGTH=10
+
+# Load config if exists
+if [ -f "$CONFIG_FILE" ]; then
+  MIN_SESSION_LENGTH=$(jq -r '.min_session_length // 10' "$CONFIG_FILE")
+  configured_path=$(jq -r '.learned_skills_path // empty' "$CONFIG_FILE")
+  if [ -n "$configured_path" ]; then
+    LEARNED_SKILLS_PATH=$(echo "$configured_path" | sed "s|~|$HOME|")
+    case "$LEARNED_SKILLS_PATH" in
+      /*) ;;
+      *) LEARNED_SKILLS_PATH="${ROOT}/${LEARNED_SKILLS_PATH}" ;;
+    esac
+  fi
+fi
+
+# Ensure learned skills directory exists
+mkdir -p "$LEARNED_SKILLS_PATH"
+
+# Get transcript path from environment (set by Claude Code)
+transcript_path="${CLAUDE_TRANSCRIPT_PATH:-}"
+
+if [ -z "$transcript_path" ] || [ ! -f "$transcript_path" ]; then
+  exit 0
+fi
+
+# Count messages in session
+message_count=$(grep -c '"type":"user"' "$transcript_path" 2>/dev/null || echo "0")
+
+# Skip short sessions
+if [ "$message_count" -lt "$MIN_SESSION_LENGTH" ]; then
+  echo "[ContinuousLearning] Session too short ($message_count messages), skipping" >&2
+  exit 0
+fi
+
+# Signal to Claude that session should be evaluated for extractable patterns
+echo "[ContinuousLearning] Session has $message_count messages - evaluate for extractable patterns" >&2
+echo "[ContinuousLearning] Save learned skills to: $LEARNED_SKILLS_PATH" >&2