docs(se): add SE-15 Foundational Coding Principles article Adds a new article covering 25 core coding principles missing from the existing SE series: - KISS, YAGNI, DRY - Separation of Concerns, Encapsulation, Abstraction, Modularity - High Cohesion / Low Coupling - Boy Scout Rule, Fail Fast, Defensive Programming - Principle of Least Astonishment - Automation, Immutability, Observability - Performance as a Feature, Concurrent & Parallel Thinking - Documentation is Part of the Code, Feedback Loops - Summary mottoes and a "How These Principles Interact" section Updates SE-01, SE-14, and the index to link to the new article. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

buddhika75 committed Jun 9, 2026