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/auth/auth.test.ts

@@ -0,0 +1,58 @@
+import { test, expect } from "bun:test"
+import { Auth } from "../../src/auth"
+
+test("set normalizes trailing slashes in keys", async () => {
+  await Auth.set("https://example.com/", {
+    type: "wellknown",
+    key: "TOKEN",
+    token: "abc",
+  })
+  const data = await Auth.all()
+  expect(data["https://example.com"]).toBeDefined()
+  expect(data["https://example.com/"]).toBeUndefined()
+})
+
+test("set cleans up pre-existing trailing-slash entry", async () => {
+  // Simulate a pre-fix entry with trailing slash
+  await Auth.set("https://example.com/", {
+    type: "wellknown",
+    key: "TOKEN",
+    token: "old",
+  })
+  // Re-login with normalized key (as the CLI does post-fix)
+  await Auth.set("https://example.com", {
+    type: "wellknown",
+    key: "TOKEN",
+    token: "new",
+  })
+  const data = await Auth.all()
+  const keys = Object.keys(data).filter((k) => k.includes("example.com"))
+  expect(keys).toEqual(["https://example.com"])
+  const entry = data["https://example.com"]!
+  expect(entry.type).toBe("wellknown")
+  if (entry.type === "wellknown") expect(entry.token).toBe("new")
+})
+
+test("remove deletes both trailing-slash and normalized keys", async () => {
+  await Auth.set("https://example.com", {
+    type: "wellknown",
+    key: "TOKEN",
+    token: "abc",
+  })
+  await Auth.remove("https://example.com/")
+  const data = await Auth.all()
+  expect(data["https://example.com"]).toBeUndefined()
+  expect(data["https://example.com/"]).toBeUndefined()
+})
+
+test("set and remove are no-ops on keys without trailing slashes", async () => {
+  await Auth.set("anthropic", {
+    type: "api",
+    key: "sk-test",
+  })
+  const data = await Auth.all()
+  expect(data["anthropic"]).toBeDefined()
+  await Auth.remove("anthropic")
+  const after = await Auth.all()
+  expect(after["anthropic"]).toBeUndefined()
+})