Add Debian packaging support for socktop-agent (#25)

* Add Debian packaging support with cargo-deb

- Add cargo-deb metadata to socktop and socktop_agent Cargo.toml
- Create systemd service file for socktop_agent
- Add postinst/postrm maintainer scripts for user/group management
- Create GitHub Actions workflow to build .deb packages for AMD64 and ARM64
- Add comprehensive documentation in docs/DEBIAN_PACKAGING.md
- Packages will be available as artifacts on every push
- Automatic GitHub releases for version tags

* Add summary documentation for debian packaging

* fix unit test, move to macro cargo_bin!

* hotfix for issue with socktop agent not creating ssl certificate on first launch after upgrade of axum server version.

* Add helpful post-install message to guide users on enabling socktop-agent service

* Fix CI build by installing libdrm development dependencies

* Fix package rename script - cargo-deb already includes architecture in filename

* Make GPU support optional to enable RISC-V builds without libdrm

- Add 'gpu' feature flag (enabled by default)
- Make gfxinfo dependency optional
- Provide no-op GPU metrics when gpu feature disabled
- Disable GPU support for RISC-V builds in CI (libdrm unavailable)
- All other architectures (amd64, arm64, armhf) still get GPU support

* feature gate GPU stats for arm v7

* specify correct package names.

* install aarch64-linux-gnu-gcc build dep

* specify correct package name

* add RISC-V GCC compiler

* add .cargo to gitignore to elimicate issue with riscv64-linux-gnu-gcc linker in config.toml

* add gcc-arm-linux-gnueabihf linker fore armv7

* set correct x-compile lib gcc-aarch64-linux-gnu for arm64 builds.

* add ports.ubuntu.com to sources

* Add ARM64 as a foreign architecture

* fixe for ARM64 build.

* security.ubuntu.com` aNNOYING

* apt repo github page

* copy output to apt repo

* fix secrets path

* fix secrets path

* change build dep

* Fix postinst message box alignment

* ci(deb): restrict APT publish to v* release tags

Previously the workflow built and published on every push to master
and feature/debian-packaging in addition to v* tags. That meant the
gh-pages APT repo got overwritten on every commit with same-version
.debs, causing apt clients to see a phantom "update available" each
time and burning ~5-10 min of cross-compile CI per merge.

After this change:
  - PRs into master still cross-build .debs as a sanity check.
  - v* tags build, publish to gh-pages, and create a GitHub release.
  - workflow_dispatch remains as the manual escape hatch.
  - master pushes no longer trigger this workflow (ci.yml still runs).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.gitignore

@@ -1,7 +1,16 @@
 /target
 .vscode/
 /socktop-wasm-test/target
+/.cargo/
 
 # Documentation files from development sessions (context-specific, not for public repo)
 /OPTIMIZATION_PROCESS_DETAILS.md
 /THREAD_SUPPORT.md
+
+# APT Repository - Safety: Never commit private keys!
+*.asc
+*-private.key
+*-secret.key
+gpg-private-backup.key
+secring.gpg
+# Note: Release.gpg, InRelease, and KEY.gpg (public) ARE safe to commit