fix: ChatBubble crash and DeepSeek API compatibility

- Fix ChatBubble to handle non-string content with String() wrapper
- Fix API route to use generateText for non-streaming requests
- Add @ai-sdk/openai-compatible for non-OpenAI providers (DeepSeek, etc.)
- Use Chat Completions API instead of Responses API for compatible providers
- Update ChatBubble tests and fix component exports to kebab-case
- Remove stale PascalCase ChatBubble.tsx file

_bmad-output/planning-artifacts/ux_brainstorm_notes.md

@@ -0,0 +1,17 @@
+# UX Brainstorming Notes
+**Date:** 2026-01-20
+**Context:** Pre-PRD Brainstorming
+
+## Core Interaction
+- **Chat Interface:** "WhatsApp-style" chat. Familiar, fast, low friction.
+- **Input Method:** Mobile-first text entry (likely voice later, but text focus now).
+
+## The "Magic Moment" (Review)
+- **Layout:** Side-by-side view.
+- **Interaction:** User sees raw "vent" on one side (or top) and "generated post" on the other.
+- **Comparison:** Easy to see the transformation from "messy thought" to "polished content".
+
+## Visual Vibe & Aesthetics
+- **Platform:** Mobile-first, but must be responsive for PC display.
+- **Style:** "Gamified but with more pastel colors."
+- **Tone:** Friendly, approachable, not "hacker/terminal" dark mode. Soft, encouraging.