Fix CI: pnpm PATH, Obsidian arch matcher, Arch pkg names, Fedora lazygit COPR

- post.go: export PNPM_HOME+PATH before pnpm add -g so global bins
  install correctly in the non-interactive shell. Applied to
  installNpmPackage and installPlaywright (incl. browser install).
- system.go: treat token-less Obsidian AppImage as x86_64 (upstream
  publishes "Obsidian-X.Y.Z.AppImage" with no arch suffix).
- pkgmgr.go: docker-ce-rootless-extras and vagrant are AUR-only on
  Arch → skipOverride; pipx → python-pipx on pacman.
- repos.go: new setupLazygitCoprRepo enables copr.fedorainfracloud.org/
  dejan/lazygit on Fedora; wired into repoGroups so lazygit installs.
- Tests: PNPM_HOME export (Linux+macOS), token-less Obsidian asset,
  pacman pkg overrides, COPR repo setup, updated repoGroups count.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

pkgmgr.go

@@ -105,7 +105,8 @@ var packageOverrides = map[string]map[string]overrideEntry{
 		"containerd.io":             replace("containerd"),
 		"docker-ce":                 replace("docker"),
 		"docker-ce-cli":             skipOverride(), // covered by docker
-		"docker-ce-rootless-extras": replace("docker-rootless-extras"),
+		"docker-ce-rootless-extras": skipOverride(), // AUR-only
+		"pipx":                      replace("python-pipx"),
 		"docker-buildx-plugin":      replace("docker-buildx"),
 		"docker-compose-plugin":     replace("docker-compose"),
 		"dotnet-sdk-10.0":           replace("dotnet-sdk"),
@@ -121,7 +122,7 @@ var packageOverrides = map[string]map[string]overrideEntry{
 		"rg":                        replace("ripgrep"),
 		"shutter":                   skipOverride(), // AUR-only
 		"temurin-25-jdk":            replace("jdk-openjdk"),
-		"vagrant":                   replace("vagrant"),
+		"vagrant":                   skipOverride(), // AUR-only
 		"vivaldi-stable":            replace("vivaldi"),
 		"webcamoid":                 skipOverride(), // AUR-only; provided via Flatpak when --gui
 		"wireshark":                 replace("wireshark-qt"),