Follow-up cleanup to the unified-default flip (#8802, #8803, #8804).
Unified rendering is now the default and the unified property is
@deprecated/@ignore, so the public API docs and examples shouldn't be
framed around "unified mode" any more — it's just gsplat rendering.

Engine source:
- GSplatComponent: remove the "## Unified Rendering" section from the
  class JSDoc; strip the JSDoc blocks from material get/set and
  highQualitySH get/set (both are legacy-only and only documented the
  unified/non-unified distinction). Drop "unified" qualifiers from
  workBufferUpdate, workBufferModifier, setParameter, and
  getInstanceTexture JSDocs.
- GSplatComponentSystem: drop "in unified mode" from the
  material:created and frame:ready event JSDocs, and from the
  getMaterial JSDoc.
- GSplatParams: rename "Parameters for GSplat unified system" to
  "Parameters for the GSplat system"; drop "unified" qualifier from
  dataFormat, material, and format JSDocs.
- GSplatContainer: drop "non-unified rendering" from the class example
  comment, drop unified: true from the addComponent example, drop
  "unified" qualifier from the centers JSDoc.

Examples (gaussian-splatting folder):
- Remove unified: true from every addComponent('gsplat', { ... }) call
  (~40 occurrences across 29 files) — it's now the default and the
  property is deprecated.
- Reword/remove comments that mention "unified" framing now that it's
  just the standard path (e.g. "Create hotel gsplat with unified set
  to true" → "Create hotel gsplat").
- Drop three stale orbit-pivot comments ("unified gsplats have no mesh
  AABB for focusEntity framing") — these became factually incorrect
  once #8803 made orbit-camera unified-aware.
- Update global-sorting example header from "demonstrates unified
  gsplat rendering" to "demonstrates global gsplat sorting" to reflect
  what the example actually shows.

Remaining "unified" mentions in the engine are all either internal
(private fields, code comments, code branches), runtime warning strings
(which must keep the property name), @ignore'd JSDoc, or directory
names — none render in public docs.

Co-authored-by: Martin Valigursky <mvaligursky@snapchat.com>

The quad gsplat renderer applies an anti-aliasing opacity factor when
GSPLAT_AA is enabled, but the hybrid (GPU-sort) renderer ignored it.
Since the hybrid path projects in a compute pass and rasterizes from a
cache, the AA factor is computed in the projector and baked into the
cached alpha, so the hybrid VS and cache layout are unchanged.

The AA variant is gated to non-pick mode (picking only gates on a binary
opacity threshold), keeping the projector variant count to 12 not 16.

Also adds an Anti-alias toggle to the gsplat viewer example's Renderer
panel, wired to GSplatParams#antiAlias.

Co-authored-by: Martin Valigursky <mvaligursky@snapchat.com>
Co-authored-by: Claude Opus 4.7 <noreply@anthropic.com>

GSplatSortBinWeights is stringified via toString() and injected into the
unified sorter's Worker blob. With esbuild's target: 'es2020', public
class fields are transpiled into __publicField() helper calls (minified
to n). The helper lives only in the main bundle, so when the class runs
inside the worker the constructor throws "ReferenceError: n is not
defined" on its first field assignment.

Move all five instance fields into the constructor as plain
this.x = ... assignments so the class stays self-contained when
stringified.

Fixes #8806.

Co-authored-by: Martin Valigursky <mvaligursky@snapchat.com>