Rename styling vocabulary to Styles and reshape style types

[kmcginnes]

Description

Renames the *Preferences* styling vocabulary to the Styles convention and reshapes the style types around a visual base + type-only extension — a pure refactor with no behavior change. This is slice 1 of the User Default Styles epic (#1881): it establishes the vocabulary and type partition the later slices build on.

The style types now compose from two pieces:

• VertexVisualStyle / EdgeVisualStyle — all-required visual fields (the resolved baseline a rendered entity always has, and the future type-less default).
• VertexTypeStyle / EdgeTypeStyle — type-only fields (display label + attribute selectors).

The stored and resolved per-type models recompose from these: VertexStyleStorage / EdgeStyleStorage (Partial<Visual & Type> & { type }) and VertexStyle / EdgeStyle (Readonly<Visual & Type & { type }>). These are type-equivalent to the old *PreferencesStorageModel / *Preferences shapes — verified by pnpm check:types and the unchanged test suite.

Renamed throughout: *Preferences* → *Style* (types, atoms, hooks); defaultVertex/EdgePreferences → appDefaultVertex/EdgeStyle; createVertex/EdgePreference → resolveVertex/EdgeStyle; the storage-model suffix standardizes on Storage; userPreferences.ts → graphStyles.ts. The Cytoscape intermediate render types NodeStyle / EdgeStyle become RenderedNodeStyle / RenderedEdgeStyle to free the clean domain names. Module names (NodesStyling/EdgesStyling), the "customize" verb, and all storage keys are unchanged.

Agent docs kept in sync: the CONTEXT.md styles glossary, docs/agents/testing.md, and dated addendums on two ADRs mapping old→new identifiers (decision bodies left immutable).

Stacked on #1879 (base styles-import-export). Review/merge that first; this PR's diff is only the rename.

How to read

1. packages/graph-explorer/src/core/StateProvider/graphStyles.ts — the heart of the change: the reshaped types (visual base + type extension), the renamed appDefault*Style / resolve*Style / *StyleAtom symbols, and the cascade doc.
2. packages/graph-explorer/src/components/Graph/Graph.model.ts — the Cytoscape NodeStyle/EdgeStyle → Rendered*Style rename that frees the domain names.
3. packages/graph-explorer/src/core/ConfigurationProvider/types.ts — how VertexTypeConfig/EdgeTypeConfig compose the renamed storage models.
4. packages/graph-explorer/src/core/StateProvider/configuration.ts — the merge that consumes them (order unchanged, just renamed types).
5. CONTEXT.md — glossary now speaks the new code names. The rest of the diff is mechanical consumer + test renames.

Validation

• pnpm checks passes (types + lint + format, 0 errors).
• pnpm test passes (2037 tests / 176 files). Existing styling tests pass unchanged aside from renamed symbols.
• Pure rename: no user-facing string, storage key, or file-format field altered; cascade resolution order preserved.

Related Issues

• Closes Rename styling vocabulary to the Styles convention and reshape style types #1866
• Part of User Default Styles: type-less global styling #1881

Check List

• I confirm that my contribution is made under the terms of the Apache 2.0 license.
• I have verified pnpm checks passes with no errors.
• I have verified pnpm test passes with no failures.
• I have covered new added functionality with unit tests if necessary.
• I have updated documentation if necessary.