Refactor theme onto bread-theme; add bakery.toml and release workflow

- Cargo.toml: depend on bread-theme (path dep for local dev, git dep for
  production) with gtk feature; remove local theme dependencies
- src/theme.rs: replace local pywal/Catppuccin impl with bread_theme::gtk
  helpers; local bar-specific CSS is preserved
- bakery.toml: describes breadbar for bakery install
- release.yml: builds on hestia self-hosted runner, publishes binary to
  dl.breadway.dev and GitHub Releases on v* tags

Cargo.toml

@@ -10,6 +10,9 @@ keywords = ["wayland", "hyprland", "bar", "status-bar", "gtk4"]
 categories = ["gui"]
 
 [dependencies]
+# Path dep for local dev; replace with git dep on first tag:
+# bread-theme = { git = "https://github.com/Breadway/bread-ecosystem", tag = "theme-v0.1.0", features = ["gtk"] }
+bread-theme = { path = "../bread-ecosystem/bread-theme", features = ["gtk"] }
 gtk4 = { version = "0.11", features = ["v4_12"] }
 gtk4-layer-shell = "0.8"
 relm4 = { version = "0.11", features = ["macros"] }