docs: add UI patterns guidance and update gitignore

- Add UI Patterns section to AGENTS.md (read docs/UI_LAYOUT.md before changes)
- Ignore .vscode/launch.json in gitignore

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

.gitignore

@@ -119,3 +119,4 @@ secrets/
 # Uploads (reference images, not tracked)
 uploads/
 logs/
+.vscode/launch.json

AGENTS.md

@@ -51,4 +51,12 @@ This document contains instructions and documentation references for AI assistan
 
 ### 📝 Changelog Maintenance
 * **Update `CHANGELOG.md`** with every user-facing change.
-* Format: `## [Unreleased] - YYYY-MM-DD` followed by `### Added`, `### Changed`, or `### Fixed`.
+* Format: `## [Unreleased] - YYYY-MM-DD` followed by `### Added`, `### Changed`, or `### Fixed`.
+
+### 🎨 UI Patterns (MUST READ BEFORE CHANGES)
+
+* **Before modifying the widget tree**, read `docs/UI_LAYOUT.md` to understand established patterns.
+* Investigate existing implementations in the codebase before creating new components.
+* **DO NOT** reinvent wheels - check if shared components already exist in `lib/shared/components/`.
+* Look at similar features for reference patterns (e.g., how other list views, forms, or CRUD screens are built).
+* Deviating from established patterns creates inconsistency and technical debt.