Refine gel/blob gradient rendering and interaction polish

[Jesssullivan]

Problem

The current SVG renderer is compact and functional, but the next design pass needs smoother gel/blob gradients, better highlight behavior, and interaction cleanup without inflating the package or making the visuals noisy.

Scope

• Review current BlobSVG.svelte layering, radial gradients, blur filters, blend modes, and opacity curves.
• Tune gel body, glow, and core highlight behavior for light and dark modes.
• Keep renderer output deterministic enough for tests and screenshots.
• Avoid broad theme churn until interaction physics is stable.

Validation

• Local Vite demo visual review.
• Screenshot checks across light/dark and desktop/mobile viewports.
• pnpm build, pnpm check, pnpm test, and package surface checks remain green.

[Jesssullivan]

Gel/blob rendering polish is implemented locally.\n\nWhat changed:\n- Scoped BlobSVG filter and gradient IDs with Svelte's component id helper so multiple TinyVectors instances do not collide in document-level SVG defs.\n- Reworked the SVG stack into bounded glow, soft body, off-center specular highlight, and inner color-depth layers.\n- Added explicit layout styles for TinyVectors and BlobSVG so plain CSS consumers and the local demo are not dependent on Tailwind utility classes for full-bleed rendering.\n- Added dev harness query params for reproducible screenshot states: theme, dark, blobs, animated, pointerPhysics, scrollPhysics, deviceMotion, and controls=false.\n- Tuned the dev demo typography and controls so mobile captures do not overlap the primary content.\n\nResearch notes used:\n- MDN SVG filters: filters compose primitive layers and feGaussianBlur is the right primitive for controlled softening: https://developer.mozilla.org/en-US/docs/Web/SVG/Guides/SVG_filters\n- W3C SVG 1.1 filter effects: filter regions clip large blurs, so the new filters use explicit bounded user-space regions: https://www.w3.org/TR/SVG11/filters.html\n- MDN radial gradient/spread behavior: kept default padded radial gradients and used focal offsets rather than heavier filter primitives: https://developer.mozilla.org/en-US/docs/Web/SVG/Reference/Attribute/spreadMethod\n\nVisual checks:\n- Headless Chrome desktop dark screenshot: /tmp/tinyvectors-dark-desktop-4.png\n- Headless Chrome mobile light screenshot: /tmp/tinyvectors-light-mobile-5.png\n\nValidation passed: pnpm check, pnpm test, pnpm build, pnpm check:release-metadata, pnpm check:package, pnpm audit --audit-level low, git diff --check, nix flake check --no-build, nix develop . --command bazel build //:pkg //:typecheck //:test --verbose_failures, npm pack --dry-run ./bazel-bin/pkg, and npm publish --dry-run --ignore-scripts --access public ./bazel-bin/pkg.

[Jesssullivan]

Working-tree update, not committed yet:

• Scoped SVG gradient/filter IDs per component instance with $props.id() to avoid collisions across multiple rendered blobs.
• Reworked the blob rendering into bounded glow, soft edge, body, specular highlight, and inner depth layers.
• Added explicit root sizing/display styles so the Svelte component is less dependent on external utility CSS.

Svelte check, unit tests, build, Bazel, package lint, npm pack, and npm publish dry-run all pass locally.

[Jesssullivan]

Gel/blob visual QA update:

• Rendered desktop/mobile screenshots after the current gel layer work.
• Blob gradients/filters render cleanly under the Tinyland dark background; no filter ID collisions or visible clipping were observed in the CDP captures.
• The only issue found was dev harness control layout on mobile-size captures, so the cleanup stayed in dev/index.html and dev/App.svelte rather than touching core gel/physics code.
• Validation still passes: check, full unit tests, production build, browser motion probe, and diff whitespace check.

[Jesssullivan]

Planning update: rendering polish should follow TIN-853 / #40. Gel/fluid is a visual language for a background system, not a mandate for a heavier fluid simulation. Keep the restored three-layer renderer as the v0.3 baseline; future polish should be tokenized/stylable and validated against flashing/noise in the local demo.

[Jesssullivan]

Scroll interaction cleanup pushed: 1a6a1e4 fix(scroll): honor max pull-force config.

ScrollHandlerConfig.maxForces now actually caps retained pull forces, including 0 to disable retained pull forces while preserving stickiness. Defaults remain unchanged: normal forces retain 8, explosive forces retain 10.

Validation refreshed locally: pnpm run check, pnpm run test (173 tests), pnpm run build, pnpm run check:bundle-size (10.78 KiB gzip, 0.22 KiB target headroom), and pnpm run test:browser:motion.