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/format/format.test.ts

@@ -0,0 +1,172 @@
+import { Effect } from "effect"
+import { afterEach, describe, expect, test } from "bun:test"
+import { tmpdir } from "../fixture/fixture"
+import { withServices } from "../fixture/instance"
+import { Bus } from "../../src/bus"
+import { File } from "../../src/file"
+import { Format } from "../../src/format"
+import * as Formatter from "../../src/format/formatter"
+import { Instance } from "../../src/project/instance"
+
+describe("Format", () => {
+  afterEach(async () => {
+    await Instance.disposeAll()
+  })
+
+  test("status() returns built-in formatters when no config overrides", async () => {
+    await using tmp = await tmpdir()
+
+    await withServices(tmp.path, Format.layer, async (rt) => {
+      const statuses = await rt.runPromise(Format.Service.use((s) => s.status()))
+      expect(Array.isArray(statuses)).toBe(true)
+      expect(statuses.length).toBeGreaterThan(0)
+
+      for (const s of statuses) {
+        expect(typeof s.name).toBe("string")
+        expect(Array.isArray(s.extensions)).toBe(true)
+        expect(typeof s.enabled).toBe("boolean")
+      }
+
+      const gofmt = statuses.find((s) => s.name === "gofmt")
+      expect(gofmt).toBeDefined()
+      expect(gofmt!.extensions).toContain(".go")
+    })
+  })
+
+  test("status() returns empty list when formatter is disabled", async () => {
+    await using tmp = await tmpdir({
+      config: { formatter: false },
+    })
+
+    await withServices(tmp.path, Format.layer, async (rt) => {
+      const statuses = await rt.runPromise(Format.Service.use((s) => s.status()))
+      expect(statuses).toEqual([])
+    })
+  })
+
+  test("status() excludes formatters marked as disabled in config", async () => {
+    await using tmp = await tmpdir({
+      config: {
+        formatter: {
+          gofmt: { disabled: true },
+        },
+      },
+    })
+
+    await withServices(tmp.path, Format.layer, async (rt) => {
+      const statuses = await rt.runPromise(Format.Service.use((s) => s.status()))
+      const gofmt = statuses.find((s) => s.name === "gofmt")
+      expect(gofmt).toBeUndefined()
+    })
+  })
+
+  test("service initializes without error", async () => {
+    await using tmp = await tmpdir()
+
+    await withServices(tmp.path, Format.layer, async (rt) => {
+      await rt.runPromise(Format.Service.use(() => Effect.void))
+    })
+  })
+
+  test("status() initializes formatter state per directory", async () => {
+    await using off = await tmpdir({
+      config: { formatter: false },
+    })
+    await using on = await tmpdir()
+
+    const a = await Instance.provide({
+      directory: off.path,
+      fn: () => Format.status(),
+    })
+    const b = await Instance.provide({
+      directory: on.path,
+      fn: () => Format.status(),
+    })
+
+    expect(a).toEqual([])
+    expect(b.length).toBeGreaterThan(0)
+  })
+
+  test("runs enabled checks for matching formatters in parallel", async () => {
+    await using tmp = await tmpdir()
+
+    const file = `${tmp.path}/test.parallel`
+    await Bun.write(file, "x")
+
+    const one = {
+      extensions: Formatter.gofmt.extensions,
+      enabled: Formatter.gofmt.enabled,
+      command: Formatter.gofmt.command,
+    }
+    const two = {
+      extensions: Formatter.mix.extensions,
+      enabled: Formatter.mix.enabled,
+      command: Formatter.mix.command,
+    }
+
+    let active = 0
+    let max = 0
+
+    Formatter.gofmt.extensions = [".parallel"]
+    Formatter.mix.extensions = [".parallel"]
+    Formatter.gofmt.command = ["sh", "-c", "true"]
+    Formatter.mix.command = ["sh", "-c", "true"]
+    Formatter.gofmt.enabled = async () => {
+      active++
+      max = Math.max(max, active)
+      await Bun.sleep(20)
+      active--
+      return true
+    }
+    Formatter.mix.enabled = async () => {
+      active++
+      max = Math.max(max, active)
+      await Bun.sleep(20)
+      active--
+      return true
+    }
+
+    try {
+      await withServices(tmp.path, Format.layer, async (rt) => {
+        await rt.runPromise(Format.Service.use((s) => s.init()))
+        await Bus.publish(File.Event.Edited, { file })
+      })
+    } finally {
+      Formatter.gofmt.extensions = one.extensions
+      Formatter.gofmt.enabled = one.enabled
+      Formatter.gofmt.command = one.command
+      Formatter.mix.extensions = two.extensions
+      Formatter.mix.enabled = two.enabled
+      Formatter.mix.command = two.command
+    }
+
+    expect(max).toBe(2)
+  })
+
+  test("runs matching formatters sequentially for the same file", async () => {
+    await using tmp = await tmpdir({
+      config: {
+        formatter: {
+          first: {
+            command: ["sh", "-c", 'sleep 0.05; v=$(cat "$1"); printf \'%sA\' "$v" > "$1"', "sh", "$FILE"],
+            extensions: [".seq"],
+          },
+          second: {
+            command: ["sh", "-c", 'v=$(cat "$1"); printf \'%sB\' "$v" > "$1"', "sh", "$FILE"],
+            extensions: [".seq"],
+          },
+        },
+      },
+    })
+
+    const file = `${tmp.path}/test.seq`
+    await Bun.write(file, "x")
+
+    await withServices(tmp.path, Format.layer, async (rt) => {
+      await rt.runPromise(Format.Service.use((s) => s.init()))
+      await Bus.publish(File.Event.Edited, { file })
+    })
+
+    expect(await Bun.file(file).text()).toBe("xAB")
+  })
+})