deprecate: make the idalib worker the default backend; mark mcp path for removal

Opening a binary now defaults to our own idalib worker; the ida-pro-mcp HTTP
supervisor path is deprecated (kept only for --db/attach and --backend mcp).

* launch.py: --backend default resolves to worker for a fresh binary open, mcp
  for the attach modes (--db / bare `ida-tui`, which have no worker equivalent);
  explicit --backend or IDATUI_BACKEND still wins. Logs a deprecation notice when
  the mcp path is used.
* Deprecation markers on client.py and server/patch_server.py; the ida-tui shell
  header and README now describe the worker as primary and note
  $IDATUI_WORKER_PYTHON. TODO tracks the removal checklist.

No code deleted yet — the mcp fallback stays until the worker is proven on a box
where idalib can spawn (pilot against --backend worker is the gate). Backend
resolution matrix verified: `ida-tui bash`->worker, bare/`--db`->mcp, explicit
flag/env honored.

1 files changed, 7 insertions, 2 deletions

diff --git a/README.md b/README.md
index ac9c680..2789105 100644
--- a/README.md
+++ b/README.md
@@ -1,8 +1,13 @@
 # ida-tui
 
 A minimal, keyboard-first (mouse-capable) **TUI frontend for IDA Pro**, built with
-[Textual](https://textual.textualize.io/) and talking to the
-[ida-pro-mcp](https://github.com/mrexodia/ida-pro-mcp) (idalib) server.
+[Textual](https://textual.textualize.io/) and driving **idalib** (IDA headless).
+
+Opening a binary now spawns our own **idalib worker** — a private subprocess
+talking a unix socket (`idatui/worker.py` + `WorkerClient`), ~50–100× cheaper per
+call than the old transport. The
+[ida-pro-mcp](https://github.com/mrexodia/ida-pro-mcp) HTTP path is **deprecated**
+(kept behind `--backend mcp` / `--db` attach) and slated for removal.
 
 ## ⚠️ Status: not ready for public consumption