fix: Omit raw format from direct asset URLs

[kof]

Summary

Generate direct project-asset URLs without ?format=raw, regardless of whether the asset is an image, video, font, document, text file, or another supported format. Runtime asset URLs remain root-relative, while optimized Image components add explicit transformation parameters only when they actually request a transformation.

Root cause

Direct URLs encoded the absence of transformation as format=raw. That mixed a no-operation decision into every asset URL and made passthrough depend on a query flag instead of the absence of requested operations.

Implementation

• Generate direct optimized-image URLs as /cgi/image/<asset> with no query parameters.
• Generate all other direct asset URLs as /cgi/asset/<asset> with no query parameters.
• Change the image-loader passthrough contract from { format: "raw" } to a parameterless { src } request.
• Remove format=raw from page social images and imported Inception image URLs.
• Keep runtime asset URLs root-relative across origins.
• Keep explicit resizing, quality, fit, gravity, and output-format transformations unchanged.
• Continue accepting legacy proxied URLs containing format=raw as loader inputs.

Todo

• Add regression expectations and demonstrate they fail against the previous URL generators.
• Remove format=raw from direct URLs for every supported asset format.
• Preserve root-relative runtime URLs for Markdown and asset resources.
• Preserve explicit transformations added by Image component loaders.
• Remove remaining direct-URL format=raw producers in social images and imported images.
• Run SDK, image, React SDK, Builder, asset-repository, and CLI tests/typechecks.
• Run formatting, targeted lint, and git diff --check.
• Run the complete fixture sync/build pipeline and inspect its output; no fixture files changed.
• Review authoritative Builder documentation. This simplifies an internal URL contract without changing a documented user workflow, so no documentation update is required.

Verification

• pnpm --filter @webstudio-is/sdk test -- assets.test.ts
• pnpm --filter @webstudio-is/image test -- image-optimize.test.ts image-loaders.test.ts
• pnpm --filter @webstudio-is/builder test -- app/shared/copy-paste/asset-upload.test.tsx app/builder/features/text-file-editor/markdown-preview.test.tsx
• pnpm --filter @webstudio-is/asset-uploader test -- asset-repository.test.ts
• pnpm --filter webstudio test -- asset-files.test.ts prebuild.test.ts
• SDK, image, React SDK, Builder, and CLI typechecks
• Targeted oxlint and oxfmt --check
• pnpm fixtures
• git diff --check

Regression expectations were run against the previous implementations and failed because direct URLs still emitted ?format=raw; they pass with this change. Agent evaluations were not run because evaluation approval was not requested.

Dependency and deployment order

Depends on webstudio-is/webstudio-saas#654. Merge and deploy that worker change before releasing this Builder change; otherwise a parameterless image-route request would still receive the old default 256px transformation.

Closes #6014