test: add a local Docker test environment for all features

testenv/ starts two real NetBox 4.7 instances (v2 and v1 token), SSH
targets on public, mgmt, and prod networks, a jump host, an IPv6-only
host, a static host, and a client with ssh, sftp, scp, tmux, zellij,
bash, zsh, and fish. A seed script fills NetBox through the REST API.

141 end-to-end checks cover cache and refresh filters, connecting,
all resolver strategies, multiple instances, shortcuts and rewrites,
SSH options and rules, static hosts, sftp/scp incl. IPv6 and jump
hosts, tunnels, local notes and NetBox comments, completion and shell
hooks, the TUI (driven through tmux), the configurator, and uninstall.

Local only: testenv/up.sh, test.sh, shell.sh, down.sh. Not part of
CI/CD.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

testenv/tests/14-uninstall.sh

@@ -0,0 +1,12 @@
+# Uninstall in dry-run mode lists everything netssh created.
+config <<'EOF'
+resolver: {strategies: [primary_ip]}
+EOF
+check "refresh" netssh cache refresh
+check "hook install" netssh hook install --shell bash
+expect_out "lists the profile" ".bashrc" netssh uninstall --dry-run
+expect_out "lists the config" "netssh.yaml" netssh uninstall --dry-run
+expect_out "lists the cache" ".cache/netssh" netssh uninstall --dry-run
+out=$(netssh uninstall --dry-run --keep-config 2>&1)
+[[ $out != *"netssh.yaml"* ]] && ok "--keep-config keeps the config" || bad "--keep-config keeps the config" "$out"
+expect_out "nothing was removed" "netssh shell-init" cat "$HOME/.bashrc"