chore: inital commit

Split project into a Cargo workspace with two crates:

- core/ (noctua_core): UI-independent document library
- ui/ (noctua_ui): COSMIC application scaffold (empty)

justfile for workspace (run, run-cli, check, test, build)

core/Cargo.toml

@@ -0,0 +1,48 @@
+# SPDX-License-Identifier: GPL-3.0-or-later
+# core/Cargo.toml
+#
+# Core library crate – no UI dependencies.
+
+[package]
+name = "noctua_core"
+version = "0.1.0"
+edition = "2021"
+description = "Document core library for the Noctua viewer"
+repository = "https://codeberg.org/wfx/noctua"
+authors = ["Wolfgang Morawetz <wfx@mailbox.org>"]
+license = "GPL-3.0-or-later"
+
+[lib]
+name = "noctua_core"
+path = "src/lib.rs"
+
+[features]
+default = ["image", "vector", "portable"]
+image = ["dep:image", "dep:kamadak-exif"]
+vector = ["dep:resvg"]
+portable = ["dep:pdfium-render"]
+full = ["image", "vector", "portable"]
+
+[dependencies]
+# Serialization
+serde = { version = "1", features = ["derive"] }
+ron = "0.8"
+
+# Feature-gated document backends
+image = { version = "0.25", optional = true }
+kamadak-exif = { version = "0.5", optional = true }
+pdfium-render = { version = "0.8", optional = true }
+resvg = { version = "0.45", optional = true }
+
+# Logging interface
+log = "0.4"
+
+# Thumbnail cache (freedesktop.org spec)
+dirs = "5.0"
+md5 = "0.7"
+png = "0.17"
+
+[dev-dependencies]
+# CLI test harness (examples/cli.rs only)
+clap = { version = "4", features = ["derive"] }
+env_logger = "0.11"