[P4d] Build setup + TUI registration for token-meter

[four-bytes-robby]

Purpose

Add two-phase build (tsc for TUI + Bun.build for server), update package.json exports, register TUI component, and update documentation.

Scope

Build (scripts/build.ts)

• Phase 1: bunx tsc — compiles TUI files with JSX preserved → dist/tui.jsx + .d.ts
• Phase 2: Bun.build() — bundles server entry point → dist/four-opencode-token-budget-guard.js
• Adapt from deepseek-meter's build.ts pattern

package.json

• Add dependencies: @opentui/solid, solid-js, @four-bytes/opencode-plugin-lib
• Add exports map:

{
  "exports": {
    "./server": { "types": "./dist/four-opencode-token-budget-guard.d.ts", "import": "./dist/four-opencode-token-budget-guard.js" },
    "./tui": { "types": "./dist/tui.d.ts", "import": "./dist/tui.jsx" }
  }
}

• Update build script: "build": "bun run scripts/build.ts"

tsconfig.json

• Add: "jsx": "preserve", "jsxImportSource": "@opentui/solid"

TUI registration

• Document in README: add file:// path to tui.json
• opencode plugin -g for npm installs

README update

• Document token_meter_status tool
• Document TUI sidebar (screenshot placeholder, configuration, tui.json entry)
• Follow README_TEMPLATE.md conventions

Files

• scripts/build.ts (new)
• package.json (modify)
• tsconfig.json (modify)
• README.md (modify)

Acceptance

• bun run build produces correct dist/ files
• TUI component loads in opencode sidebar
• No JSX transform errors
• README documents all changes