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/file/fsmonitor.test.ts

@@ -0,0 +1,62 @@
+import { $ } from "bun"
+import { describe, expect, test } from "bun:test"
+import fs from "fs/promises"
+import path from "path"
+import { File } from "../../src/file"
+import { Instance } from "../../src/project/instance"
+import { tmpdir } from "../fixture/fixture"
+
+const wintest = process.platform === "win32" ? test : test.skip
+
+describe("file fsmonitor", () => {
+  wintest("status does not start fsmonitor for readonly git checks", async () => {
+    await using tmp = await tmpdir({ git: true })
+    const target = path.join(tmp.path, "tracked.txt")
+
+    await fs.writeFile(target, "base\n")
+    await $`git add tracked.txt`.cwd(tmp.path).quiet()
+    await $`git commit -m init`.cwd(tmp.path).quiet()
+    await $`git config core.fsmonitor true`.cwd(tmp.path).quiet()
+    await $`git fsmonitor--daemon stop`.cwd(tmp.path).quiet().nothrow()
+    await fs.writeFile(target, "next\n")
+    await fs.writeFile(path.join(tmp.path, "new.txt"), "new\n")
+
+    const before = await $`git fsmonitor--daemon status`.cwd(tmp.path).quiet().nothrow()
+    expect(before.exitCode).not.toBe(0)
+
+    await Instance.provide({
+      directory: tmp.path,
+      fn: async () => {
+        await File.status()
+      },
+    })
+
+    const after = await $`git fsmonitor--daemon status`.cwd(tmp.path).quiet().nothrow()
+    expect(after.exitCode).not.toBe(0)
+  })
+
+  wintest("read does not start fsmonitor for git diffs", async () => {
+    await using tmp = await tmpdir({ git: true })
+    const target = path.join(tmp.path, "tracked.txt")
+
+    await fs.writeFile(target, "base\n")
+    await $`git add tracked.txt`.cwd(tmp.path).quiet()
+    await $`git commit -m init`.cwd(tmp.path).quiet()
+    await $`git config core.fsmonitor true`.cwd(tmp.path).quiet()
+    await $`git fsmonitor--daemon stop`.cwd(tmp.path).quiet().nothrow()
+    await fs.writeFile(target, "next\n")
+
+    const before = await $`git fsmonitor--daemon status`.cwd(tmp.path).quiet().nothrow()
+    expect(before.exitCode).not.toBe(0)
+
+    await Instance.provide({
+      directory: tmp.path,
+      fn: async () => {
+        await File.read("tracked.txt")
+      },
+    })
+
+    const after = await $`git fsmonitor--daemon status`.cwd(tmp.path).quiet().nothrow()
+    expect(after.exitCode).not.toBe(0)
+  })
+})