refactor: apply minimal tfcode branding

- Rename packages/opencode → packages/tfcode (directory only)
- Rename bin/opencode → bin/tfcode (CLI binary)
- Rename .opencode → .tfcode (config directory)
- Update package.json name and bin field
- Update config directory path references (.tfcode)
- Keep internal code references as 'opencode' for easy upstream sync
- Keep @opencode-ai/* workspace package names

This minimal branding approach allows clean merges from upstream
opencode repository while providing tfcode branding for users.

packages/tfcode/test/bun.test.ts

@@ -0,0 +1,53 @@
+import { describe, expect, test } from "bun:test"
+import fs from "fs/promises"
+import path from "path"
+
+describe("BunProc registry configuration", () => {
+  test("should not contain hardcoded registry parameters", async () => {
+    // Read the bun/index.ts file
+    const bunIndexPath = path.join(__dirname, "../src/bun/index.ts")
+    const content = await fs.readFile(bunIndexPath, "utf-8")
+
+    // Verify that no hardcoded registry is present
+    expect(content).not.toContain("--registry=")
+    expect(content).not.toContain("hasNpmRcConfig")
+    expect(content).not.toContain("NpmRc")
+  })
+
+  test("should use Bun's default registry resolution", async () => {
+    // Read the bun/index.ts file
+    const bunIndexPath = path.join(__dirname, "../src/bun/index.ts")
+    const content = await fs.readFile(bunIndexPath, "utf-8")
+
+    // Verify that it uses Bun's default resolution
+    expect(content).toContain("Bun's default registry resolution")
+    expect(content).toContain("Bun will use them automatically")
+    expect(content).toContain("No need to pass --registry flag")
+  })
+
+  test("should have correct command structure without registry", async () => {
+    // Read the bun/index.ts file
+    const bunIndexPath = path.join(__dirname, "../src/bun/index.ts")
+    const content = await fs.readFile(bunIndexPath, "utf-8")
+
+    // Extract the install function
+    const installFunctionMatch = content.match(/export async function install[\s\S]*?^  }/m)
+    expect(installFunctionMatch).toBeTruthy()
+
+    if (installFunctionMatch) {
+      const installFunction = installFunctionMatch[0]
+
+      // Verify expected arguments are present
+      expect(installFunction).toContain('"add"')
+      expect(installFunction).toContain('"--force"')
+      expect(installFunction).toContain('"--exact"')
+      expect(installFunction).toContain('"--cwd"')
+      expect(installFunction).toContain("Global.Path.cache")
+      expect(installFunction).toContain('pkg + "@" + version')
+
+      // Verify no registry argument is added
+      expect(installFunction).not.toContain('"--registry"')
+      expect(installFunction).not.toContain('args.push("--registry')
+    }
+  })
+})