Strip surrounding quotes from CLI paths for Windows CMD (#91)

## Summary

Fixes #86

- Windows CMD does not strip single quotes from arguments, so `--home
'C:\Users\foo'` passes the literal value `'C:\Users\foo'` (quotes
included), producing broken paths like `'C:\Users\foo'\config.toml`
- `expandPath()` now strips matching surrounding single or double quotes
before processing, covering `--home`, `--config`, and `MSGVAULT_HOME`
paths

## Test plan

- [x] `TestExpandPath` — new cases for single-quoted, double-quoted,
mismatched, and single-char inputs
- [x] `make lint` — clean
- [x] `make test` — all pass

🤖 Generated with [Claude Code](https://claude.com/claude-code)

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: wesm

internal/config/config.go

@@ -6,6 +6,7 @@ import (
 	"log/slog"
 	"os"
 	"path/filepath"
+	"runtime"
 	"strings"
 
 	"github.com/BurntSushi/toml"
@@ -237,10 +238,20 @@ func resolveRelative(path, base string) string {
 
 // expandPath expands ~ to the user's home directory.
 // Only expands paths that are exactly "~" or start with "~/".
+// It also strips surrounding single or double quotes, which Windows CMD
+// passes through literally (unlike Unix shells which strip them).
 func expandPath(path string) string {
 	if path == "" {
 		return path
 	}
+	// Strip surrounding quotes left by Windows CMD (e.g. --home 'C:\Users\foo').
+	// Only on Windows — Unix shells strip quotes before the process sees them,
+	// and literal quote characters in Unix paths are valid (if unusual).
+	if runtime.GOOS == "windows" && len(path) >= 2 &&
+		((path[0] == '\'' && path[len(path)-1] == '\'') ||
+			(path[0] == '"' && path[len(path)-1] == '"')) {
+		path = path[1 : len(path)-1]
+	}
 	if path == "~" || strings.HasPrefix(path, "~"+string(os.PathSeparator)) || strings.HasPrefix(path, "~/") {
 		home, err := os.UserHomeDir()
 		if err != nil {

internal/config/config_test.go

@@ -15,10 +15,11 @@ func TestExpandPath(t *testing.T) {
 	}
 
 	tests := []struct {
-		name     string
-		input    string
-		expected string
-		unixOnly bool // skip on Windows (uses Unix-style absolute paths)
+		name        string
+		input       string
+		expected    string
+		unixOnly    bool // skip on Windows (uses Unix-style absolute paths)
+		windowsOnly bool // skip on non-Windows (quote stripping is Windows-only)
 	}{
 		{
 			name:     "empty string",
@@ -50,6 +51,34 @@ func TestExpandPath(t *testing.T) {
 			input:    "~//foo",
 			expected: filepath.Join(home, "foo"),
 		},
+		{
+			name:        "single-quoted path (Windows CMD)",
+			input:       `'C:\Users\wesmc\testing'`,
+			expected:    `C:\Users\wesmc\testing`,
+			windowsOnly: true,
+		},
+		{
+			name:        "double-quoted path (Windows CMD)",
+			input:       `"C:\Users\wesmc\testing"`,
+			expected:    `C:\Users\wesmc\testing`,
+			windowsOnly: true,
+		},
+		{
+			name:        "single-quoted tilde path",
+			input:       "'~/custom-data'",
+			expected:    filepath.Join(home, "custom-data"),
+			windowsOnly: true,
+		},
+		{
+			name:     "mismatched quotes not stripped",
+			input:    `'C:\Users\wesmc"`,
+			expected: `'C:\Users\wesmc"`,
+		},
+		{
+			name:     "single char not stripped",
+			input:    "'",
+			expected: "'",
+		},
 		{
 			name:     "absolute path unchanged",
 			input:    "/var/log/test",
@@ -79,6 +108,9 @@ func TestExpandPath(t *testing.T) {
 			if tt.unixOnly && runtime.GOOS == "windows" {
 				t.Skip("skipping Unix-specific path test on Windows")
 			}
+			if tt.windowsOnly && runtime.GOOS != "windows" {
+				t.Skip("skipping Windows-specific path test on non-Windows")
+			}
 			got := expandPath(tt.input)
 			if got != tt.expected {
 				t.Errorf("expandPath(%q) = %q, want %q", tt.input, got, tt.expected)