Add best practices, hooks, memory files, and scripts from recent sessions

Includes: spec-driven and test-driven development best practices,
reproduce-before-fixing debugging workflow, require-plan-file hook,
find-project-root script, session logs, memory files for decisions/
gotchas/process-lessons, and updates to existing best practice topics.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.gitignore

@@ -0,0 +1,8 @@
+# Vim swap files
+*.swp
+*.swo
+*~
+
+# OS files
+.DS_Store
+Thumbs.db