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_test.go

@@ -91,8 +91,15 @@ func TestResolveSystemPkgs(t *testing.T) {
 	if len(resolved) != 2 || resolved[0] != "btop" || resolved[1] != "ripgrep" {
 		t.Errorf("expected [btop ripgrep], got %v", resolved)
 	}
-	if len(skipped) != 1 || skipped[0] != "buildah" {
-		t.Errorf("expected skipped to be [buildah], got %v", skipped)
+	// pacman: docker-ce-rootless-extras and vagrant are AUR-only -> skipped;
+	// pipx is replaced with python-pipx.
+	pkgMgr = "pacman"
+	resolved, skipped = resolveSystemPkgs([]string{"docker-ce-rootless-extras", "vagrant", "pipx", "rg"})
+	if len(resolved) != 2 || resolved[0] != "python-pipx" || resolved[1] != "ripgrep" {
+		t.Errorf("expected [python-pipx ripgrep], got %v", resolved)
+	}
+	if len(skipped) != 2 || skipped[0] != "docker-ce-rootless-extras" || skipped[1] != "vagrant" {
+		t.Errorf("expected skipped [docker-ce-rootless-extras vagrant], got %v", skipped)
 	}
 }