fix(docs): drop non-existent com.apple.security.screen-capture entitlement (#144)

The README told users to add com.apple.security.screen-capture to
their Entitlements.plist alongside com.apple.security.app-sandbox.
That entitlement key does not exist — Apple's entitlement reference
has never defined a screen-capture entitlement. ScreenCaptureKit is
gated by the user's TCC grant in System Settings, requested via
NSScreenCaptureUsageDescription in Info.plist; no code-signing
entitlement is required on signed or sandboxed apps.

Rewrite the Requirements section to:
  - document the required Info.plist key (with example string),
  - call out explicitly that no com.apple.security.screen-capture
    entitlement exists,
  - keep the sandbox entitlement note for apps that opt into the
    App Sandbox.

Update the Troubleshooting row 'App crashes after notarization' to
point at the actual cause (missing NSScreenCaptureUsageDescription)
instead of recommending the fake entitlement.

The Tauri example's Entitlements.plist already documents this
correctly (see examples/22_tauri_app/src-tauri/Entitlements.plist);
this commit brings the top-level README in line.

Fixes #144

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: 1313

README.md

@@ -355,12 +355,24 @@ Screen capture **always requires user permission**. To grant it:
 2. Enable your binary (during development this is usually your terminal or IDE)
 3. Restart the app
 
-For distribution, add `NSScreenCaptureUsageDescription` to `Info.plist` and the
-appropriate entitlements:
+For distribution, add a purpose string to `Info.plist` — the user-facing
+TCC prompt requires it and the app will be terminated without one:
+
+```xml
+<key>NSScreenCaptureUsageDescription</key>
+<string>Capture your screen so the app can …</string>
+```
+
+ScreenCaptureKit itself does **not** require a code-signing entitlement
+on either signed or sandboxed apps — capture is gated by the user's TCC
+grant in **System Settings → Privacy & Security → Screen & System
+Audio Recording**, not by an `Entitlements.plist` key. (There is no
+`com.apple.security.screen-capture` entitlement; that key does not
+exist in Apple's entitlement reference.) If your app is sandboxed you
+still need the sandbox entitlement itself:
 
 ```xml
 <key>com.apple.security.app-sandbox</key>      <true/>
-<key>com.apple.security.screen-capture</key>   <true/>
 ```
 
 ## Performance
@@ -422,7 +434,7 @@ numbers at various resolutions, and tuning guidance.
 | Black / empty frames | Captured window minimized; pixel format mismatch; filter doesn't include the right display/window |
 | No audio samples | Did you set `.with_captures_audio(true)` **and** add a handler for `SCStreamOutputType::Audio`? |
 | Build fails with Swift bridge errors | `xcode-select --install`; then `cargo clean && cargo build` |
-| App crashes after notarization | Add the `screen-capture` entitlement (see [Requirements](#requirements--permissions)) |
+| App crashes after notarization | Missing `NSScreenCaptureUsageDescription` in `Info.plist` — the system terminates apps that trigger the Screen Recording TCC prompt without one (see [Requirements](#requirements--permissions)) |
 | `match` on `PixelFormat` / `SCStreamErrorCode` no longer compiles | Both are `#[non_exhaustive]` in 2.0 — add a wildcard `_ => …` arm |
 
 ## Migration