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/fixture/lsp/fake-lsp-server.js

@@ -0,0 +1,77 @@
+// Simple JSON-RPC 2.0 LSP-like fake server over stdio
+// Implements a minimal LSP handshake and triggers a request upon notification
+
+const net = require("net")
+
+let nextId = 1
+
+function encode(message) {
+  const json = JSON.stringify(message)
+  const header = `Content-Length: ${Buffer.byteLength(json, "utf8")}\r\n\r\n`
+  return Buffer.concat([Buffer.from(header, "utf8"), Buffer.from(json, "utf8")])
+}
+
+function decodeFrames(buffer) {
+  const results = []
+  let idx
+  while ((idx = buffer.indexOf("\r\n\r\n")) !== -1) {
+    const header = buffer.slice(0, idx).toString("utf8")
+    const m = /Content-Length:\s*(\d+)/i.exec(header)
+    const len = m ? parseInt(m[1], 10) : 0
+    const bodyStart = idx + 4
+    const bodyEnd = bodyStart + len
+    if (buffer.length < bodyEnd) break
+    const body = buffer.slice(bodyStart, bodyEnd).toString("utf8")
+    results.push(body)
+    buffer = buffer.slice(bodyEnd)
+  }
+  return { messages: results, rest: buffer }
+}
+
+let readBuffer = Buffer.alloc(0)
+
+process.stdin.on("data", (chunk) => {
+  readBuffer = Buffer.concat([readBuffer, chunk])
+  const { messages, rest } = decodeFrames(readBuffer)
+  readBuffer = rest
+  for (const m of messages) handle(m)
+})
+
+function send(msg) {
+  process.stdout.write(encode(msg))
+}
+
+function sendRequest(method, params) {
+  const id = nextId++
+  send({ jsonrpc: "2.0", id, method, params })
+  return id
+}
+
+function handle(raw) {
+  let data
+  try {
+    data = JSON.parse(raw)
+  } catch {
+    return
+  }
+  if (data.method === "initialize") {
+    send({ jsonrpc: "2.0", id: data.id, result: { capabilities: {} } })
+    return
+  }
+  if (data.method === "initialized") {
+    return
+  }
+  if (data.method === "workspace/didChangeConfiguration") {
+    return
+  }
+  if (data.method === "test/trigger") {
+    const method = data.params && data.params.method
+    if (method) sendRequest(method, {})
+    return
+  }
+  if (typeof data.id !== "undefined") {
+    // Respond OK to any request from client to keep transport flowing
+    send({ jsonrpc: "2.0", id: data.id, result: null })
+    return
+  }
+}