v1.3.0 — Linux support

First release carrying the Linux (WebKitGTK) port — feat/linux-port is now merged into main.

Linux (new)

• Full desktop port: window, tray, notifications, quick replies, scheduler, webhooks, MCP endpoint — same feature set as Windows, rendered with WebKitGTK 4.1
• Install: sudo dpkg -i wagramdesklite_1.3.0_amd64.deb (Ubuntu/Debian; pulls libwebkit2gtk-4.1-0) or run the standalone WaGramDeskLite-linux-amd64 binary
• Screenshot paste works around WebKit bug 218519 — install xclip or wl-clipboard so the OS clipboard bridge can deliver images
• Smoke-tested under Xvfb: launches and runs clean

Platform pairing

• Every non-shared source file now carries an explicit //go:build windows or //go:build linux tag; no runtime.GOOS branching anywhere
• internal/paste gained a Windows stub — it was the only package that failed an explicit GOOS=windows build ("build constraints exclude all Go files")
• scripts/build.sh now pins GOOS=windows: running it on Linux previously crashed the Go linker (-H windowsgui forced a PE link over ELF objects)

Windows

• Version metadata 1.3.0 (VERSIONINFO, installer script, compiled resources)
• No functional changes beyond the build fix above

Verified

• go build / go vet / go test green on GOOS=linux and GOOS=windows
• WaGramDeskLite.exe is a fresh PE32+ GUI build with embedded 1.3.0 metadata

SHA256SUMS.txt attached. Note: WaGramDeskLiteSetup.exe is not included this time — the Inno Setup compiler only runs on Windows; the executable and .deb are complete installers in their own right.