fix(#152-follow-up): claw init rejects trailing arguments

## What Was Broken

`claw init foo` silently accepted the `foo` argument instead of rejecting it at parse time:

    $ claw init foo
    Init
      Project          /path/to/project
      .claw/           skipped

Trailing args should be rejected like other no-arg verbs (status, sandbox, etc.):

    $ claw status bar
    [error-kind: cli_parse]
    error: unrecognized argument `bar` for subcommand `status`

## Root Cause

The `init` arm (main.rs:1191) was missing a `rest.len()` guard.
Compare to `status` (main.rs:1319 in parse_diagnostic_verb), which correctly
rejects extra args.

## What This Fix Does

Add a simple length guard before constructing the CliAction::Init:

    "init" => {
        if rest.len() > 1 {
            return Err(format!(
                "unrecognized argument \`{}\` for subcommand \`init\`",
                rest[1]
            ));
        }
        Ok(CliAction::Init { output_format })
    }

## Dogfood Verification

Before:
    $ claw init foo
    Init
      Project          /path/to/project

After:
    $ claw init foo
    [error-kind: cli_parse]
    error: unrecognized argument `foo` for subcommand `init`

    $ claw init
    Init
      Project          /path/to/project
      (continues normally)

## Non-Regression

- `claw init` (no args) still works
- All 180 binary tests pass
- All 466 library tests pass

## Related

- #152 (diagnostic verb suffix guard)
- Follows pattern from parse_diagnostic_verb() guard clauses

rust/crates/rusty-claude-cli/src/main.rs

@@ -1188,7 +1188,16 @@ fn parse_args(args: &[String]) -> Result<CliAction, String> {
         "system-prompt" => parse_system_prompt_args(&rest[1..], output_format),
         "acp" => parse_acp_args(&rest[1..], output_format),
         "login" | "logout" => Err(removed_auth_surface_error(rest[0].as_str())),
-        "init" => Ok(CliAction::Init { output_format }),
+        "init" => {
+            // #152: init is a no-arg verb. Reject unexpected suffixes like `claw init foo`.
+            if rest.len() > 1 {
+                return Err(format!(
+                    "unrecognized argument `{}` for subcommand `init`",
+                    rest[1]
+                ));
+            }
+            Ok(CliAction::Init { output_format })
+        }
         "export" => parse_export_args(&rest[1..], output_format),
         "prompt" => {
             let prompt = rest[1..].join(" ");