Update dependencies, add WebP support, and fix export & viewport bugs

[slimbuck]

Brings the project up to date after a long gap, adds WebP input/output, and fixes several latent bugs found along the way.

Dependencies

• Updated all dependencies to their latest compatible versions, including major bumps: @playcanvas/pcui 5→6, typescript 5→6, concurrently 9→10, plus playcanvas 2.15→2.19, rollup, @typescript-eslint/*, and others.
• Held back where required: @rollup/plugin-typescript stays at 12.1.4 (12.3.0 breaks the build with an outDir/Rollup dir error — already excluded in Renovate), eslint stays on 9.x (9.39.4) because @playcanvas/eslint-config's bundled eslint-plugin-import has no eslint 10 support yet, and rollup-plugin-sass stays at 1.15.3 (its only newer release is a pre-release RC).
• tsconfig.json: removed the unused baseUrl and switched moduleResolution to bundler to clear TypeScript 6 deprecation warnings. The stricter resolution surfaced a few real null-safety issues, now fixed (texture-view.ts texSize, main.ts root element, *.scss ambient declaration).
• npm audit is clean (0 vulnerabilities).

WebP support

• Input: .webp files now load and inspect (added to the file-browser allowlist; the engine decodes WebP natively via the browser).
• Output: new "Export to WebP" button producing lossless WebP, backed by libwebp compiled to WebAssembly (static/lib/webp, shared with @playcanvas/splat-transform).

Bug fixes

• PNG export could hang forever on a worker failure: the encode promise had no reject path and the worker had no error handling. It now reports errors back, rejects properly, and the worker blob URL is revoked.
• A failed or hung export left the Export panel permanently disabled with the button stuck on "BUSY...": the export flow is now wrapped in try/finally so UI state always restores.
• Closing a texture left a grey square in the viewport and stale nullxnull/??? text in the status bar: the empty document is no longer rendered and the info bar resets to its empty state.

Testing

Verified with npm run build, npm run lint, and in-browser: WebP load (lossy + lossless fixtures) and a lossless export round-trip, PNG export still works, and the close-texture flow returns to a clean blank state.

[Copilot]

Pull request overview

This PR modernizes the toolchain/dependencies, adds WebP import/export support, and addresses a few UI/viewport/export reliability issues uncovered by stricter TypeScript resolution and export worker failure modes.

Changes:

• Updated major dev dependencies (PCUI v6, TypeScript v6, Rollup, PlayCanvas, ESLint ecosystem) and adjusted TS config (moduleResolution: bundler, removed unused baseUrl).
• Added WebP support end-to-end: .webp allowlist, new WebP exporter backed by static/lib/webp WASM module, and an “Export to WebP” UI button.
• Improved robustness/UX around export and empty-document rendering: error paths for PNG worker + try/finally UI re-enable; viewport/info panel resets when no texture is selected.

Reviewed changes

Copilot reviewed 10 out of 14 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
tsconfig.json	Switches TS module resolution to bundler and removes unused baseUrl.
static/lib/webp/webp.mjs	Adds the libwebp WASM JS loader module.
src/webp-exporter.ts	Implements lossless WebP encoding via the WASM module.
src/texture-view.ts	Prevents rendering artifacts by hiding the mesh instance when no texture is loaded; improves null-safety for texSize.
src/png-exporter.ts	Adds proper worker error reporting/rejection and revokes the worker Blob URL.
src/main.ts	Adds a non-null assertion for the #root element under stricter TS checks.
src/info-panel.ts	Resets the info bar to an empty state when no texture is selected.
src/files-browser-panel.ts	Allows .webp files in the image filename allowlist.
src/export-panel.ts	Adds “Export to WebP” and hardens export UI state with try/finally + error logging.
src/declaration.d.ts	Declares *.scss modules for bundler-handled style imports.
README.md	Documents WebP support in export features and supported formats list.
package.json	Updates dev dependency versions (including major bumps).
package-lock.json	Locks updated dependency tree for the bumped packages.

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