fix: correct inspector package name in Dockerfiles and add .dockerignore (#50)

* chore: remove inspect.sandboxagent.dev in favor of /ui/

* chore: add 404 page

* fix: correct inspector package name in Dockerfiles and add .dockerignore

- Change @anthropic-ai/sdk-inspector to @sandbox-agent/inspector in all Dockerfiles
- Add .dockerignore to exclude target/, node_modules/, etc from Docker context

The wrong package name caused pnpm install --filter to match nothing, so the
inspector frontend was never built, resulting in binaries without the /ui/ endpoint.

* chore: cargo fmt

* chore(release): update version to 0.1.4-rc.7

README.md

@@ -52,7 +52,7 @@ The Sandbox Agent acts as a universal adapter between your client application an
 |-----------|-------------|
 | **Server** | Rust daemon (`sandbox-agent server`) exposing the HTTP + SSE API |
 | **SDK** | TypeScript client with embedded and server modes |
-| **Inspector** | [inspect.sandboxagent.dev](https://inspect.sandboxagent.dev) for browsing sessions and events |
+| **Inspector** | Built-in UI at inspecting sessions and events |
 | **CLI** | `sandbox-agent` (same binary, plus npm wrapper) mirrors the HTTP endpoints |
 
 ## Get Started
@@ -172,7 +172,7 @@ npx sandbox-agent --help
 
 ### Inspector
 
-Debug sessions and events with the [Inspector UI](https://inspect.sandboxagent.dev).
+Debug sessions and events with the built-in Inspector UI (e.g., `http://localhost:2468/ui/`).
 
 ![Sandbox Agent Inspector](./.github/media/inspector.png)