docs: add partial Trinity sprite overlay prompt package (WIP)

WHAT WAS DONE:
- Started trinity-sprite-overlay-prompt-package.md
- File is incomplete - session ended early due to model switch
- Contains: usage instructions, universal specs (partial)
- Does NOT yet contain: individual character prompts for
  Wizard, Emissary, Catalyst

WHY INCOMPLETE:
Session was running on Claude Sonnet 4.6 which consumes too much
of Michael's usage quota. Switching to Sonnet 4.5 for all
Firefrost sessions going forward.

NEXT CHRONICLER:
Complete this file. Three characters need full prompt sections:
- The Wizard (Frost/cyan, black hair, graying beard, ice armor)
- The Emissary (Fire/orange, ginger hair, flame armor)
- The Catalyst (Arcane/purple, purple hair, crystal armor)
Reference: docs/branding/trinity-skins/README.md for exact specs
Reference images already searched this session (see session context)

Signed-off-by: Chronicler #45 <claude@firefrostgaming.com>

docs/branding/trinity-sprite-overlay-prompt-package.md

@@ -0,0 +1,36 @@
+# Trinity Sprite & Overlay Artwork — Prompt Package
+
+**Created:** March 28, 2026  
+**Created By:** Chronicler #45  
+**Purpose:** Generate illustrated cartoon character sprites for The Trinity — for use as stream overlays, video intros/outros, social media posts, and animated sprite bases  
+**Style:** Illustrated / cartoon, transparent PNG cutouts, multiple poses per character  
+**Skin Reference:** Closely matches official Minecraft skins in `docs/branding/trinity-skins/`
+
+---
+
+## 🎯 HOW TO USE THIS PACKAGE
+
+### What You Need
+- **Gemini** (image generation) or equivalent AI image tool
+- The **5 reference images** listed in each character section
+- The **prompt text** for each character
+
+### Process (Per Character)
+1. Open a fresh Gemini session
+2. Upload the reference images listed for that character
+3. Paste the prompt
+4. Generate
+5. If result needs refinement, note what's off and adjust
+
+### One Character Per Session
+Generate each character separately — The Wizard, The Emissary, The Catalyst. Don't try to generate all three at once. You'll get better individual results and more control over each character.
+
+---
+
+## 📐 UNIVERSAL SPECIFICATIONS
+
+Apply these to ALL three characters:
+
+**Style:** Illustrated cartoon / stylized digital art — NOT photorealistic. Think animated series art style: clean lines, bold colors, expressive faces, slightly stylized proportions. Similar energy to animated show character design or high-quality Twitch VTuber artwork.
+
+**Background:** Completely transparent (PNG with alpha channel). No background elements, no shadows cast on