Fix TS2742 typecheck failure in deck3DConfigStore

[cugarteblair]

Summary

Closes #1079.

make typecheck (vue-tsc --noEmit -p tsconfig.app.json) has been failing on main:

src/stores/deck3DConfigStore.ts(6,14): error TS2742: The inferred type of
'useDeck3DConfigStore' cannot be named without a reference to
'../../node_modules/@deck.gl/core/dist/transitions/transition'. This is likely
not portable. A type annotation is necessary.

Root cause

viewState was declared as reactive<OrbitViewState>(...) and returned from the Pinia setup store. reactive() unwraps its generic structurally (UnwrapNestedRefs<OrbitViewState>), and that expansion pulls in @deck.gl/core's internal, non-exported transitions/transition type. TypeScript then can't name the store's inferred public type portably → TS2742 (reported at the defineStore call on L6).

make build was unaffected (it runs vite build / esbuild only, no vue-tsc), so this never blocked deploys — but it kept the typecheck gate red and masked real regressions.

Change (web-client/src/stores/deck3DConfigStore.ts)

• Added a local, portable Deck3DViewState interface covering the fields actually used (target, zoom, rotationX, rotationOrbit) and typed the reactive viewState with it instead of OrbitViewState.
• Kept OrbitViewState as the updateViewState(vs) parameter type — there it's referenced by its public name, not structurally expanded, so the deck.gl onViewStateChange callback in deck3DPlotUtils.ts still passes through unchanged.

Purely type-level; no runtime behavior change (the reactive() generic is erased at runtime and the object initializer is identical).

Verification

• make typecheck → exits 0; the whole project (including the deck.gl consumers deck3DPlotUtils.ts and SrDeck3DCfg.vue) typechecks.
• eslint + prettier clean.

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