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>

scripts/install-hooks.sh

@@ -40,6 +40,12 @@ cat <<'EOF'
         "matcher": "Edit|Write|MultiEdit",
         "hooks": [{ "type": "command", "command": "~/.claude/hooks/post-edit-lint.sh", "timeout": 30, "statusMessage": "Formatting and linting..." }]
       }
+    ],
+    "PreToolUse": [
+      {
+        "matcher": "ExitPlanMode",
+        "hooks": [{ "type": "command", "command": "~/.claude/hooks/require-plan-file.sh" }]
+      }
     ]
   }
 }