Releases offer plain programs; the licences are built in

Release assets are now the programs themselves: SolveCraft and solvecraft-cli .exe for Windows,
plain Linux binaries plus the AppImage, a macOS .dmg (SolveCraft.app with an Applications link) and
the universal CLI binary; only the web app stays a zip. The notes template takes {tag}, says to
chmod +x on Linux and macOS, and GitHub adds the change list.

Since no LICENSE or NOTICE file rides along any more, the programs carry them:
THIRD-PARTY-LICENSES.txt (written by `cargo xtask licences` from cargo metadata and each shipped
crate's own licence files, 419 crates; `cargo xtask ci` checks it is current) is embedded with
LICENSE-MIT, LICENSE-APACHE and NOTICE in solvecraft_engine::licences, shown in Help ▸ About ▸
Licences (third-party text laid out by visible rows) and printed by `solvecraft-cli licences`.
Scenario s44_about_licences.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

CONTRIBUTING.md

@@ -59,7 +59,8 @@ The [README](README.md#architecture) has the layer table. The short version:
 2. **No GPL/LGPL/AGPL code, not even reading it.** That rules out OpenCASCADE, FreeCAD
    (including planegcs), SolveSpace, CadQuery/OCP, LibreCAD and QCAD. SolveCraft is
    MIT OR Apache-2.0, and its solver and blends are written from the maths. Permissive
-   dependencies are fine. Note which one you're adding and why in the PR.
+   dependencies are fine. Note which one you're adding and why in the PR, and run
+   `cargo xtask licences` so THIRD-PARTY-LICENSES.txt lists it (CI checks that it is current).
 3. **Every asset is original or openly licensed and has a row in
    [ATTRIBUTION.md](ATTRIBUTION.md).** Icons are drawn in code (`crates/ui-egui/src/icons.rs`).
    `cargo xtask assets` enforces this.