fix(gui): restore params.toml workspace parameter reading

[KoEkko]

Summary

• Fix a d851295 regression: WorkspaceResourceService only read home/parameters.json, so workspaces with just home/params.toml resolved an empty design name, produced artifact paths like _place.def.gz, and chip-viewer:open failed with a missing response.
• Restore a read-only workspaceParametersFile module: locate home/params.toml first with home/parameters.json fallback, flatten [design]/[pdk] TOML section mirrors per ecc workspace_config.py, and wire it into the resource index and readParameters IPC.
• Re-add smol-toml (^1.8.0, same as pre-refactor) and add TOML workspace regression tests.

Scope

Select the areas touched by this PR:

• GUI - desktop UI/runtime changes in ecos/gui, including renderer, Electron, and shared packages.
• ECC - ECC submodule updates or ECOS Studio integration with the ECC CLI/runtime.
• Resource management - resource registry, downloads, installation, manifests, PDKs, or tool assets.
• Build, packaging, Nix, or release workflow - build inputs, AppImage packaging, or release metadata.
• CI - GitHub Actions workflows, reusable actions, triggers, path filters, or automated checks.
• Documentation only - README, guides, templates, or docs with no runtime behavior change.

Validation

List the commands you ran. Mark checks that are not applicable as N/A.

• cd ecos/gui && pnpm run typecheck
• cd ecos/gui && pnpm run test
• cd ecos/gui && pnpm run build
• cd ecos/gui && pnpm run desktop:build && pnpm run desktop:smoke
• make build
• make demo-gcd
• make demo-retrosoc
• Manual GUI smoke: cd ecos/gui && pnpm run dev
• Other: python3 .github/scripts/check-version.py; cd ecos/gui && pnpm install --frozen-lockfile && pnpm run lint && pnpm run fmt:check

Skipped checks and reason:

• make build, make demo-gcd, make demo-retrosoc, manual GUI smoke: no release, packaging, version-metadata, native-resource, or ECC runtime change and no visible GUI change. desktop:smoke ran locally on the real display (no xvfb) with ELECTRON_DISABLE_SANDBOX=1 and ECOS_ELECTRON_DISABLE_GPU=1; the Linux AppImage packaging job is covered by CI.

Screenshots or Recordings

Required for visible GUI changes.

• N/A - no visible GUI change.

Release, Packaging, and Runtime Impact

• No release, packaging, or runtime impact
• Version metadata changed
• AppImage or Electron packaging changed
• ECC CLI runtime resources changed
• OSS CAD Suite, PDK, resource download, or installer behavior changed
• Submodule gitlink changed

Notes:

• Adds the smol-toml runtime dependency to @ecos-studio/desktop-electron; pnpm-lock.yaml update is included.

Checklist

• I kept the change scoped to the affected component.
• I updated docs or user-facing text where behavior changed.
• I included lockfile changes for dependency updates.
• I documented intentional submodule updates.
• I did not include local caches, virtual environments, or generated build outputs.
• I explained any skipped validation and remaining risk.