Add egui_kittest_mcp server

New binary crate that exposes an MCP (Model Context Protocol) server backed by
the `egui_inspection` protocol. The server bridges a running egui peer — a
spawned `egui_kittest` harness child process or an attached live `eframe` app —
to MCP tool handlers that drive it.

Components:
- `bridge.rs`: spawns / attaches a peer over a unix socket, runs reader+writer
  Tokio tasks that pump `HarnessMessage` ↔ `InspectorCommand` and track the
  peer's `Hello`, latest frame, accesskit tree, and blocked / finished state.
- `tools.rs`: `rmcp`-derived tool router with commands for stepping, event
  injection (click / type / scroll / hover / drag / keys), resizing, screenshot
  capture, accesskit tree queries, and lifecycle (launch / attach / kill).
- `tree.rs`: accesskit-tree projection helpers shared by the tools.
- `shim.rs` / `main.rs`: shim role that lets the same binary act as the child
  inspector for kittest harnesses, relaying bytes between the harness stdio
  and the MCP server's unix socket.
- `server.rs`: rmcp stdio entry point.

Live-app example added at `examples/egui_mcp/`.

crates/egui_kittest_mcp/Cargo.toml

@@ -0,0 +1,49 @@
+[package]
+name = "egui_kittest_mcp"
+version.workspace = true
+authors = ["Lucas Meurer <hi@lucasmerlin.me>"]
+description = "MCP server that drives egui apps via the kittest inspector protocol"
+edition.workspace = true
+rust-version.workspace = true
+homepage = "https://github.com/emilk/egui"
+license.workspace = true
+repository = "https://github.com/emilk/egui"
+categories = ["gui", "development-tools::testing"]
+keywords = ["egui", "kittest", "mcp", "testing", "accesskit"]
+publish = false
+
+[[bin]]
+name = "kittest-mcp"
+path = "src/main.rs"
+
+[dependencies]
+egui_kittest = { workspace = true, features = ["inspector_api", "wgpu", "snapshot"] }
+egui_inspection = { workspace = true, features = ["protocol"] }
+egui.workspace = true
+accesskit.workspace = true
+accesskit_consumer.workspace = true
+image = { workspace = true, features = ["png"] }
+rmp-serde.workspace = true
+serde = { workspace = true, features = ["derive"] }
+serde_json = "1.0"
+schemars = "1.0"
+rmcp = { version = "1.7", features = ["server", "macros", "transport-io", "schemars"] }
+tempfile.workspace = true
+tokio = { version = "1.49", features = [
+    "rt-multi-thread",
+    "io-std",
+    "io-util",
+    "process",
+    "net",
+    "sync",
+    "macros",
+    "time",
+    "signal",
+] }
+base64 = "0.22"
+anyhow = "1.0"
+tracing = "0.1"
+tracing-subscriber = { version = "0.3", features = ["env-filter"] }
+
+[lints]
+workspace = true