cli: read a url-like bare word as the url, not a misspelt command

`lightpanda version.io` was rejected as a misspelt `version`, 3 edits
within the length-scaled limit. Like curl, it fetches now: the command check
shares --dump's isUrlLike.

src/Config.zig

@@ -316,9 +316,7 @@ fn dumpValidator(_: Allocator, args: *std.process.Args.Iterator, target: *?DumpF
     if (peek_args.next()) |next_arg| {
         const mode = std.meta.stringToEnum(DumpFormat, next_arg) orelse {
             // Anything else is the positional url, unless it is a misspelt format.
-            // No format has a `.`, `/` or `:`, so `markdown.com` is a url.
-            const url_like = std.mem.indexOfAny(u8, next_arg, ".:/") != null;
-            if (!url_like and string.closest(next_arg, tagNames(DumpFormat)) != null) {
+            if (!cli.isUrlLike(next_arg) and string.closest(next_arg, tagNames(DumpFormat)) != null) {
                 return cli.invalidChoice("--dump", "", next_arg, tagNames(DumpFormat));
             }
             target.* = .html;
@@ -1381,6 +1379,24 @@ test "Config: parseArgs --dump tells a url from a misspelt format" {
     }
 }
 
+test "Config: parseArgs tells a url from a misspelt command" {
+    var arena = std.heap.ArenaAllocator.init(std.testing.allocator);
+    defer arena.deinit();
+
+    {
+        const argv = [_][*:0]const u8{ "lightpanda", "version.io" };
+        const proc_args: std.process.Args = .{ .vector = &argv };
+        const config = try parseArgs(arena.allocator(), proc_args);
+        try std.testing.expectEqualStrings("version.io", config.mode.fetch.url.items[0]);
+    }
+    {
+        log.expectLog(&.{.app});
+        const argv = [_][*:0]const u8{ "lightpanda", "versoin" };
+        const proc_args: std.process.Args = .{ .vector = &argv };
+        try std.testing.expectError(error.UnknownCommand, parseArgs(arena.allocator(), proc_args));
+    }
+}
+
 test "Config: validateUserAgent" {
     try validateUserAgent("Lightpanda/1.0");
     try std.testing.expectError(error.Reserved, validateUserAgent("mozilla/1.0"));

src/cli.zig

@@ -200,6 +200,12 @@ pub fn tagNames(comptime E: type) []const []const u8 {
     };
 }
 
+/// No command or choice has a `.`, `/` or `:`, so `markdown.com` is a url
+/// however close it is to `markdown`.
+pub fn isUrlLike(arg: []const u8) bool {
+    return std.mem.indexOfAny(u8, arg, ".:/") != null;
+}
+
 /// `prefix` was stripped from `value` before matching, like `--log-filter`'s sign.
 pub fn invalidChoice(arg: []const u8, prefix: []const u8, value: []const u8, choices: []const []const u8) error{InvalidArgument} {
     var value_buf: [128]u8 = undefined;
@@ -456,7 +462,7 @@ pub fn Builder(comptime commands: anytype) type {
             }
 
             // A bare word close to a command name is a typo, not a fetch url.
-            if (std.mem.startsWith(u8, cmd_str, "--") == false and string.closest(cmd_str, command_names) != null) {
+            if (std.mem.startsWith(u8, cmd_str, "--") == false and !isUrlLike(cmd_str) and string.closest(cmd_str, command_names) != null) {
                 return unknownCommand(cmd_str);
             }