feat(launcher): bundle Bun runtime with launcher artifacts

- Use private Bun runtimes for installed and downloadable launchers
- Package runtime licenses, source manifests, and corresponding source releases
- Update launcher workflows, setup, updates, and documentation

changes/bundled-bun-runtime-docs.md

@@ -0,0 +1,5 @@
+type: docs
+area: launcher
+
+- Documented private-runtime launcher installation, simplified first-run setup, custom app locations, legacy launcher migration, and package-managed updates. Updated release-note download guidance for the bundled runtime and Windows launcher.
+- Documented the bundled Bun runtime's MIT and LGPL licensing, where the notices live in the app, and the corresponding-source release asset. The AUR package now lists the bundled runtime licenses and installs their notices under `/usr/share/licenses/subminer-bin`, and `subminer-assets.tar.gz` includes the same notices.

changes/bundled-bun-runtime.md

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+type: changed
+area: launcher
+
+- Made every installed and downloadable launcher use the Bun runtime included with SubMiner. Added a Windows `subminer.cmd` download, persistent private runtime caches for Linux and Windows, and migration for recognized legacy launchers. Deferred migrations survive overlapping update checks and remain pending when startup cannot safely refresh the launcher.
+- Simplified first-run setup to a single optional launcher control, with runtime repair guidance shown only when needed.

changes/compressed-incremental-sync.md

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+type: changed
+area: sync
+
+- Sync uses compressed, incremental rsync transfers on compatible macOS and Linux machines, caching the last received snapshot per peer to reduce traffic on subsequent syncs. Cache helpers work through the launcher; older apps and launchers fall back to compressed transfers without an upload cache.
+- Machines without compatible rsync, including Windows endpoints, automatically use compressed scp transfers.
+- Rsync explicitly uses SSH and aborts transfers that exceed 30 minutes before merging.

changes/fix-first-launch-config-directory.md

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+type: fixed
+area: startup
+
+- Fixed first launch exiting on macOS when the SubMiner config directory did not yet exist by creating it before acquiring the startup lock.

changes/sync-transfer-docs.md

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+type: docs
+area: sync
+
+- Documented compressed transfers, incremental sync cache storage, and compatibility with older peers.