[CacinieP]

AppImageHub PR AppImage/appimage.github.io#11396 found that the v0.4.4 AppImage cannot start on its older Linux test host: texada-shell imports GLIBC_2.39 and bundled GUI libraries import GLIBC_2.38.

• Build Linux desktop and frozen Python sidecar on Ubuntu 22.04 (glibc 2.35), using the matching libfuse2 package.
• Build llama-server b11669 from pinned source commit 620d2225cc436ab0b001e3200e590e3b286ef9ab on the same host, instead of importing upstream Ubuntu binary requirements. Preserve version verification and stage before replacing resources.
• Reject AppDir ELF imports newer than glibc 2.35, including weak imports.
• Add PR Linux package builds and run both installed deb and extracted AppImage through existing desktop/backend/render checks inside a network namespace with only loopback enabled. Release builds use the same checks.

Validation: 44 relevant pytest cases passed; Ruff, bash syntax, actionlint and git diff checks passed. Real Linux package CI is required before merging/releasing. This PR does not replace existing published release bytes or claim the catalog retest has passed.