fix(builder): fix linter exception loading and sandbox file access

[abn]

Summary

Fixes flatpak-builder-lint exception handling during builds:

• Infers application ID from manifest before pre-build linting to ensure exceptions are matched by App ID rather than unmatched wildcard *.
• Creates consolidated linter exceptions file inside stateDir (.state/) instead of $XDG_RUNTIME_DIR//tmp, ensuring the file is accessible within Flatpak's sandboxed container execution environment.
• Adds test coverage for manifest-based App ID inference and exceptions generation in pkg/builder/builder_test.go.