## Why

The Phase 3D native client must request a bounded display mode and send
provider-neutral absolute-pointer and high-resolution scroll input. The current
wire contract exposes only policy-selected stream dimensions and rejects both
new input kinds.

## What Changes

- Add one bounded `DisplayMode` object and optional display fields to session
  request/session/manifest contracts while keeping control wire version 1.
- Register `display.request.v1`, `input.absolute.v1`, and `input.scroll.v1` so
  every new behavior is explicitly negotiated.
- Extend VGI1 with exact absolute-pointer and signed scroll bodies while
  preserving all existing kind encodings.
- Require a new immutable Protocol release candidate after deterministic
  Go/Rust/Swift generation and conformance pass; existing tags remain unchanged.

## Capabilities

### New Capabilities

- `session-display-mode`: Optional feature-gated requested and effective display
  mode disclosure for native session creation and manifests.

### Modified Capabilities

- `gateway-input-feedback`: Add negotiated provider-neutral absolute-pointer and
  high-resolution scroll kinds to the existing sequenced input grammar.

## Impact

- JSON Schema, feature registry, VGI frame documentation, fixed conformance
  fixtures, generated Go/Rust/Swift bindings, and strict validators.
- Connection Server session persistence/allocation and Data Plane input
  translation after consumers pin the immutable Protocol candidate.
- Protobuf remains unchanged because no observed consumer uses it for these
  JSON control or VGI payload paths.