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/effect/run-service.test.ts

@@ -0,0 +1,46 @@
+import { expect, test } from "bun:test"
+import { Effect, Layer, ServiceMap } from "effect"
+import { makeRunPromise } from "../../src/effect/run-service"
+
+class Shared extends ServiceMap.Service<Shared, { readonly id: number }>()("@test/Shared") {}
+
+test("makeRunPromise shares dependent layers through the shared memo map", async () => {
+  let n = 0
+
+  const shared = Layer.effect(
+    Shared,
+    Effect.sync(() => {
+      n += 1
+      return Shared.of({ id: n })
+    }),
+  )
+
+  class One extends ServiceMap.Service<One, { readonly get: () => Effect.Effect<number> }>()("@test/One") {}
+  const one = Layer.effect(
+    One,
+    Effect.gen(function* () {
+      const svc = yield* Shared
+      return One.of({
+        get: Effect.fn("One.get")(() => Effect.succeed(svc.id)),
+      })
+    }),
+  ).pipe(Layer.provide(shared))
+
+  class Two extends ServiceMap.Service<Two, { readonly get: () => Effect.Effect<number> }>()("@test/Two") {}
+  const two = Layer.effect(
+    Two,
+    Effect.gen(function* () {
+      const svc = yield* Shared
+      return Two.of({
+        get: Effect.fn("Two.get")(() => Effect.succeed(svc.id)),
+      })
+    }),
+  ).pipe(Layer.provide(shared))
+
+  const runOne = makeRunPromise(One, one)
+  const runTwo = makeRunPromise(Two, two)
+
+  expect(await runOne((svc) => svc.get())).toBe(1)
+  expect(await runTwo((svc) => svc.get())).toBe(1)
+  expect(n).toBe(1)
+})