Clipboard Transformer

### Added - **Rule groups:** (#29) Add `groups` and `group_imports` to the configuration, a versioned `/groups.json` state document, tray switches for rule-used groups with rule counts and descriptions, and `groups list` / `enable` / `disable` CLI commands. Group membership is inherited from rulesets and import edges; ignored groups and explicit group state disable the rules that depend on them. Short-form import edges accept `groups` and `ignore_imported_groups` as sibling keys, and group state may be written for an id before any rule uses it. ### Changed - **Dependencies:** Update `clap`, `zbus`, `timeago`, `schemars`, `uuid`, `log`, `futures-util`, and `ureq`, and drop the runtime's unused `thiserror` dependency. Keep the plugin-author and runtime configuration schemas on draft-07 and byte-compatible across the Schemars migration. - **Packaging/Nix:** Refresh the pinned `cachix/install-nix-action` v31 revision. ### Fixed - **Developer tooling:** Point `just gen-config-schema` at the current `config schema` CLI command. - **CI:** Keep tray icon code generation clean under the Rust 1.98 Clippy slice-chunking lints. - **Release:** Keep `cargo-release` from pushing the release commit and tag together so required main-branch checks can finish before publication. - **Linux/Tray:** Detect Flatpak once in the runtime host and pass the sandbox state into the tray backend instead of sampling the environment twice.