feat: add AI-DECLARATION.md and MIT license badge

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Co-Authored-By: Mistral Vibe <vibe@mistral.ai>

AI-DECLARATION.md

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+---
+version: "0.1.2"
+level: copilot
+processes:
+  design: assist
+  implementation: pair
+  testing: pair
+  documentation: copilot
+  review: copilot
+  deployment: assist
+---
+
+This format is based on [AI-DECLARATION.md](https://ai-declaration.md/en/0.1.2).
+
+## Notes
+
+- 

README.md

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 # kirakira
 
+[![AI-DECLARATION: copilot](https://img.shields.io/badge/䷼%20AI--DECLARATION-copilot-fee2e2?labelColor=fee2e2)](https://ai-declaration.md)
+[![License: MIT](https://img.shields.io/badge/License-MIT-yellow.svg)](https://opensource.org/licenses/MIT)
+
 A mobile client for [Smol Mail](https://smol.place), a minimalist end-to-end encrypted mail protocol: one Ed25519 identity, five operations, sealed and signed messages over a Noise_NX transport. Sibling of the reference CLI client (`https://smol.place`) and the browser client (`https://code.randogoth.com/randogoth/gsmol`).
 
 kirakira began as [FlashMail](https://github.com/sarthakkimtani/flash-mail), a Flutter UI template for a disposable-email app built on mail.tm. Its networking layer was replaced end to end with a from-scratch Smol Mail implementation (`lib/smol/`: crypto, Noise handshake, framing, client flows), and the UI was redesigned around a Material 3 theme — dark navy and mint green by default, with a matching light theme — built from a single `ColorScheme` and `AppColors` extension rather than hardcoded colors per screen.