DOC: Restore prompt file references in copilot-instructions.md

The .github/prompts/ directory contains setup-dev-env, build-ddbc,
run-tests, and create-pr prompt files. Previous commit incorrectly
removed references to them. Restore the workflow table and debug
quick reference links.

Author: dlevy-msft-sql

.github/copilot-instructions.md

@@ -12,13 +12,21 @@
 
 ## Development Workflows
 
+This repository includes detailed prompt files for common tasks. Reference these with `#`:
+
+| Task | Prompt | When to Use |
+|------|--------|-------------|
+| First-time setup | `#setup-dev-env` | New machine, fresh clone |
+| Build C++ extension | `#build-ddbc` | After modifying .cpp/.h files |
+| Run tests | `#run-tests` | Validating changes |
+| Create PR | `#create-pr` | Ready to submit changes |
+
 **Workflow order for new contributors:**
-1. Create and activate a virtual environment (`python -m venv .venv`)
-2. Install dependencies (`pip install -r requirements.txt`)
-3. Build the native extension (see Build System below)
-4. Make your changes
-5. Run tests (`python -m pytest -v`)
-6. Submit a PR
+1. `#setup-dev-env` — Set up venv and dependencies
+2. `#build-ddbc` — Build native extension
+3. Make your changes
+4. `#run-tests` — Validate
+5. `#create-pr` — Submit
 
 ## Build System and Validation
 
@@ -234,11 +242,11 @@ Exception (base)
 
 | Error | Cause | Solution |
 |-------|-------|----------|
-| `ImportError: ddbc_bindings` | Extension not built | Build native extension (see Build System) |
+| `ImportError: ddbc_bindings` | Extension not built | Run `#build-ddbc` |
 | Connection timeout | Missing env var | Set `DB_CONNECTION_STRING` |
 | `dylib not found` (macOS) | Library paths | Run `configure_dylibs.sh` |
 | `ODBC Driver not found` | Missing driver | Install Microsoft ODBC Driver 18 |
-| `ModuleNotFoundError` | Not in venv | Activate virtual environment |
+| `ModuleNotFoundError` | Not in venv | Run `#setup-dev-env` |
 
 ## Contributing Guidelines