feat: Azure Data Engineering tutorials collection (10 modules)

[Copilot]

Adds a new azure-data-engineering/ top-level directory covering the full breadth of high-demand Azure Data Engineering topics, each as a self-contained module with a README, runnable code, and sample data where applicable.

Modules

Module	Artifact
ADF	adf_pipeline_simulator.py — watermark-based Copy Activity simulation
Databricks	databricks_pyspark_demo.ipynb — PySpark transforms, window functions, Delta write
Synapse Analytics	synapse_analytics_demo.py — CETAS, incremental load, partition elimination (DuckDB local sim)
ADLS Gen2	adls_gen2_demo.py — HNS operations, ACLs, Medallion structure via Azure SDK
Delta Lake	delta_lake_demo.ipynb — CRUD, MERGE/upsert, time travel, schema evolution, transaction log
SQL & PySpark	sql_pyspark_demo.ipynb — joins, window functions, pivot/unpivot, perf tips
Python / Azure SDK	azure_sdk_demo.py — Blob Storage, Key Vault, ADF pipeline trigger + poll
Snowflake	snowflake_demo.py — COPY INTO, Snowpark, streams/tasks, time travel, zero-copy clone
Microsoft Fabric	fabric_lakehouse_demo.py — Fabric REST API, OneLake upload, SQL Analytics Endpoint
Scenario Q&A	scenario_pipeline_designer.py — 5 real-world pipeline design scenarios with model answers

Design notes

• All Azure-dependent scripts detect missing credentials and fall back to dry-run mode, printing operations rather than executing them — no Azure account required to follow along.
• Root README.md updated with a new Azure Data Engineering section linking all modules.
• snowflake/sample_orders.csv includes the total column to match the target table schema used in COPY INTO.
• Removed secret.value reference from Key Vault log call to avoid clear-text logging of sensitive data.