fix(release): repair Linux desktop cross-architecture builds

[AprilNEA]

Summary

• pin Linux native module builds to Clang 15 for Electron 43
• rebuild x64 and ARM64 dependencies with architecture-specific compiler targets
• install the ARM64 C++ cross toolchain and preserve both unpacked application layouts

Root cause

Ubuntu 22's unversioned clang resolves to Clang 14, which cannot compile Electron 43's V8 headers using std::source_location. Applying one compiler configuration to both targets also produced the wrong native binding architecture, while sequential single-architecture electron-builder invocations reused linux-unpacked.

Impact

Restores verified Linux x64 and ARM64 release artifacts without moving the build to Ubuntu 24 and raising the glibc compatibility baseline.

Verification

• pnpm check:ci
• pnpm test — 2103 passed, 5 skipped
• Build Desktop run 30537813989 — Linux packaging, artifact verification, and upload passed

[linear-code]

CODE-485