Publish sourced Fabric workspace settings chapter - #35

Summary

• publish the first full DP-700 study chapter with substantive coverage of all four workspace-settings objectives
• cover Spark, domain, OneLake, and Apache Airflow settings with concepts, decisions, examples, exam distinctions, and active recall
• add a validated Microsoft Learn source registry with nine exact sources, retrieval timestamps, SHA-256 hashes, and bidirectional chapter mappings
• record the project-wide editorial depth standard, including transformation-level coverage for future Dataflow Gen2 material
• present multiple official sources cleanly in the mobile and desktop reader

Coverage contract

• the DP-700 study guide is the measured-objective checklist
• Microsoft Learn is authoritative for Fabric behavior
• published objectives require substantive teaching material, not repeated outline bullets
• official upstream sources may supplement underlying concepts without overriding Learn for Fabric claims

Verification

• 22 Python tests passed with 94.37% coverage
• 5 browser-state tests passed
• Ruff formatting and linting passed
• mypy passed
• mobile and desktop visual review passed
• the published-chapter test asserts all four measured objective titles and sections

Closes #21
Closes #26