docs: Add README, LICENSE (GPL-3.0), prepare for public release

- README with features, build instructions, usage
- GPL-3.0 license (compatible with Slint GPLv3 tier)
- Updated Cargo.toml with license, description, repository
- Cleaned up .gitignore

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.gitignore

@@ -1 +1,5 @@
 /target
+*.swp
+*.swo
+*~
+.DS_Store

Cargo.toml

@@ -2,6 +2,9 @@
 name = "KeSp_controller"
 version = "1.0.0"
 edition = "2021"
+license = "GPL-3.0"
+description = "Cross-platform configurator for the KeSp split ergonomic keyboard"
+repository = "https://github.com/mornepousse/KeSp_controller"
 
 [dependencies]
 slint = "1"

LICENSE

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+                    GNU GENERAL PUBLIC LICENSE
+                       Version 3, 29 June 2007
+
+ Copyright (C) 2007 Free Software Foundation, Inc. <https://fsf.org/>
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
+
+                            Preamble
+
+  The GNU General Public License is a free, copyleft license for
+software and other kinds of works.
+
+  The licenses for most software and other practical works are designed
+to take away your freedom to share and change the works.  By contrast,
+the GNU General Public License is intended to guarantee your freedom to
+share and change all versions of a program--to make sure it remains free
+software for all its users.  We, the Free Software Foundation, use the
+GNU General Public License for most of our software; it applies also to
+any other work released this way by its authors.  You can apply it to
+your programs, too.
+
+  For the complete license text, see <https://www.gnu.org/licenses/gpl-3.0.txt>

README.md

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+# KeSp Controller
+
+Cross-platform configurator for the KeSp split ergonomic keyboard.
+
+Built with [Rust](https://www.rust-lang.org/) and [Slint](https://slint.dev/) UI framework.
+
+![License: GPL-3.0](https://img.shields.io/badge/License-GPLv3-blue.svg)
+
+## Features
+
+- **Keymap editor** with visual keyboard layout (loaded from firmware)
+- **Key selector** with categorized grid, Mod-Tap/Layer-Tap builders, hex input
+- **Heatmap overlay** showing key press frequency (blue to red gradient)
+- **Layer management** with switch, rename, and active indicator
+- **Tap Dance** editing (4 actions per slot)
+- **Combos** creation with visual key picker
+- **Key Overrides** with modifier checkboxes (Ctrl/Shift/Alt)
+- **Leader Keys** with sequence builder
+- **Macros** with visual step builder (key presses + delays)
+- **Statistics** (hand balance, finger load, row usage, top keys, bigrams)
+- **OTA firmware update** via USB (no programming cable needed)
+- **ESP32 flasher** (esptool-like, via programming port)
+- **Settings** with keyboard layout selector (QWERTY, AZERTY, DVORAK, etc.)
+- **Dracula theme** throughout
+
+## Download
+
+Pre-built binaries for Linux, Windows, and macOS are available on the [Releases](https://github.com/mornepousse/KeSp_controller/releases) page.
+
+## Build from source
+
+### Requirements
+
+- Rust toolchain (1.75+)
+- Linux: `libudev-dev libfontconfig1-dev`
+
+### Build
+
+```bash
+cargo build --release
+```
+
+Binary will be at `target/release/KeSp_controller`.
+
+## Usage
+
+1. Plug in your KeSp keyboard via USB
+2. Launch KeSp Controller
+3. The app auto-connects to the keyboard
+4. Use the tabs to configure: Keymap, Advanced, Macros, Stats, Settings, Flash
+
+## Keyboard compatibility
+
+Designed for the KeSp/KaSe split keyboard with:
+- USB CDC serial (VID: 0xCAFE, PID: 0x4001)
+- Binary protocol v2
+- ESP32-S3 MCU
+
+## License
+
+GPL-3.0 - See [LICENSE](LICENSE)
+
+Made with [Slint](https://slint.dev/)