094 reject bare arg name mismatch

// ============================================================================
// Test 210_094: MUST_FAIL — a BARE argument whose punned name matches NO
//   parameter must be REJECTED. This is the bare-side twin of 210_091's
//   legal `echo(v: other)`.
//
//   Koru has exactly three legal argument forms:
//     1. implicit expression for an `Expr`-typed FIRST parameter (n/a: v is i32)
//     2. explicit `name: value` — ONLY when the value cannot be punned
//     3. punning — a bare token whose name matches a parameter
//   `echo(other)` is NONE of these: `other` puns to 'other', but the only
//   parameter is 'v'. The legal spelling is `echo(v: other)` (see 210_091).
//
// CURRENT BEHAVIOR (the bug this pins): compiles clean. The emit path
//   (emitter_helpers.zig ~5975) treats a bare arg as positional and binds it
//   to parameter[idx] BY INDEX, never checking that 'other' puns to 'v'.
//   RED until the frontend rejects it. Exact diagnostic code/wording is a
//   design call (TBD with the fix); expected_patterns below is the target.
// ============================================================================

~import std/io

~event echo { v: i32 }
| out i32

~echo => out v

~event src {}
| got i32

~proc src|zig { return .{ .got = 5 }; }

~src()
| got other |> echo(other)
    | out r |> std/io:print.ln("{{ r:d }}")