Build: add a local Linux bundle command

[Habdel-Edenfield]

What this changes, and why

Adds bun run tauri:build:linux, using Tauri's native .deb and AppImage bundlers, and documents the generated artifacts, compatibility baseline and existing Wayland workaround. Windows NSIS and portable build behavior remain unchanged.

This is intentionally a reproducible local packaging route, not release automation. It follows up on #1 while the supported build baseline and package policy are still being decided.

How you verified it

• bun run build
• bun test — 161 passed
• bun run i18n
• bun run catalog
• bun run commands
• cargo check in src-tauri/
• cargo run --release --example probe_monster — 2/2 fixture files round-trip identically
• bun run tauri:build:linux
• Produced MONx_0.1.131_amd64.deb and MONx_0.1.131_amd64.AppImage
• Extracted both bundles; their generated desktop entries pass desktop-file-validate
• All dynamic libraries resolve on the Ubuntu 26.04 x86_64 build host
• AppImage and extracted .deb binary stayed running for a 10-second isolated Xvfb smoke with the existing XWayland/WebKitGTK variables
• git diff --check

Known limitations / decisions still open

• Tauri derives Debian Package: mo-nx from productName: MONx.
• MONx invokes xdg-open, but xdg-utils is not declared in the .deb and is not bundled in the AppImage.
• The Ubuntu 26.04 validation build requires GLIBC_2.39; it is not suitable as an official artifact for the documented Ubuntu 22.04+ baseline.
• CI/release uploads, RPM, package identity/dependency overrides and automatic Wayland launcher variables are intentionally out of scope pending the decisions in Build: add reproducible Linux packages #1.
• No generated binary is committed or attached.

Checklist

• Round-trip still holds — nothing reordered, normalised or dropped on save
• No hard-coded attribute spellings; the engine profile remains unchanged
• Patch version bumped in package.json, src-tauri/tauri.conf.json and src-tauri/Cargo.toml

Refs #1