feat: add netssh uninstall

Remove everything netssh and install.sh set up, also leftovers of
older versions:

- netssh blocks and unmarked legacy lines in bash, zsh, and fish
  profiles
- completion files for bash, zsh (incl. the oh-my-zsh cache), fish,
  and the command alias; files not generated by netssh are kept
- the cache directory with hosts, aliases, and per-instance caches
- the config file and local notes; the config is first copied to a
  private netssh.yaml.backup-<timestamp> because it holds API tokens
- the netssh binary; for protected paths the sudo command is printed

--keep-config keeps config and notes, --dry-run only lists the plan,
and --yes skips the confirmation.

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

internal/hook/hook.go

@@ -166,6 +166,16 @@ func isLegacyLine(line string) bool {
 	return false
 }
 
+// HasEntries reports whether the profile contains a managed block or legacy lines.
+func HasEntries(profilePath string) bool {
+	data, err := os.ReadFile(profilePath)
+	if err != nil {
+		return false
+	}
+	_, removed, err := clean(string(data), profilePath)
+	return removed || err != nil
+}
+
 // Uninstall removes legacy hook lines and complete installer-managed blocks.
 // Missing profiles are a no-op; malformed blocks leave the file unchanged.
 func Uninstall(profilePath string) (removed bool, err error) {
@@ -248,3 +258,23 @@ func writeProfile(profilePath, content string) error {
 	}
 	return nil
 }
+
+// ProfileCandidates lists every shell profile netssh or install.sh may have
+// written to, in the same order as the installer.
+func ProfileCandidates() []string {
+	home := os.Getenv("HOME")
+	zdot := zshDir()
+	paths := []string{
+		filepath.Join(home, ".bashrc"),
+		filepath.Join(home, ".bash_profile"),
+		filepath.Join(home, ".bash_login"),
+		filepath.Join(home, ".profile"),
+		filepath.Join(zdot, ".zshrc"),
+		filepath.Join(zdot, ".zprofile"),
+		filepath.Join(zdot, ".zshenv"),
+	}
+	if zdot != home {
+		paths = append(paths, filepath.Join(home, ".zshrc"), filepath.Join(home, ".zprofile"), filepath.Join(home, ".zshenv"))
+	}
+	return append(paths, filepath.Join(FishConfigDir(), "config.fish"))
+}