Preserve Unicode box-drawing characters in method stdout

Problem

When an extension model writes Unicode box-drawing characters (┌─┬┐│├┼┤└┴┘) to stdout via Deno.stdout.write or console.log, swamp replaces them with ASCII equivalents (+|-). This makes table output less visually appealing.

Current behavior

Extension model writes:

┌──────────────┬───────┬────────────────┐
│ Resource     │ Count │ Details        │
├──────────────┼───────┼────────────────┤
│ environments │ 2     │ cicd, cicd-dev │
└──────────────┴───────┴────────────────┘

User sees:

+--------------+-------+----------------+
| Resource     | Count | Details        |
+--------------+-------+----------------+
| environments | 2     | cicd, cicd-dev |
+--------------+-------+----------------+

Proposed Solution

Pass through Unicode characters from method stdout without normalization. Modern terminals universally support Unicode box-drawing characters and they produce significantly cleaner table output.

Scope

The stdout capture/relay pipeline in swamp's method execution runtime is translating or filtering non-ASCII characters before writing to the parent process stdout.