refactor: restructure to standard Go project layout (cmd/ + internal/)

- Move entry point to cmd/streamdeck-lets-go/
- Split package main into internal packages:
  - internal/deck: hardware control (Deck, events, brightness)
  - internal/render: key rendering, icons, fonts, PageManager
  - internal/web: HTTP API + embedded SPA
  - internal/daemon: event loop, autoswitch, screensaver, actions
- Add ConfigDir() to internal/config
- Export cross-package API (Deck, PageManager, WebServer, etc.)
- Move dist/arch/ → packaging/ with updated PKGBUILD/.SRCINFO
- Add Makefile (build, test, vet, fmt, install)
- Update README with new build commands and project structure
- Delete unused media.go stub

README.md

@@ -27,7 +27,9 @@
 ### Install from source
 
 ```bash
-go build -o streamdeck-lets-go .
+make build
+# or
+go build -o streamdeck-lets-go ./cmd/streamdeck-lets-go
 ```
 
 ### Run
@@ -47,7 +49,19 @@ Open `http://localhost:9090` in your browser.
 
 ---
 
-## Configuration
+## Project structure
+
+```
+cmd/streamdeck-lets-go   entry point (CLI: daemon, switch, discover)
+internal/
+  config                 JSON config model, load/save/validate
+  deck                   Stream Deck hardware: open, render, brightness, events
+  render                 Key rendering, icon/fonts, PageManager, display outputs
+  web                    HTTP API + embedded Alpine.js SPA
+  daemon                 Event loop, autoswitch, screensaver, actions, gestures
+packaging/               AUR PKGBUILD, systemd unit, udev rule
+Makefile                 build, test, vet, fmt, install
+```
 
 The config file is stored at `~/.config/streamdeck-lets-go/config.json`. You can edit it manually or through the web UI.
 
@@ -371,9 +385,9 @@ After a configurable idle period the deck dims or shows a custom image.
 ## Building from source
 
 ```bash
-git clone git@git.totmin.ru:en2zmax/streamdeck-lets-go.git
+git clone git@github.com:totmin/streamdeck-lets-go.git
 cd streamdeck-lets-go
-go build -o streamdeck-lets-go .
+make build
 ```
 
 Dependencies: