Extract demo local-folder model handling out of App.jsx

[ysdede]

Summary

Extract demo local-folder model handling out of examples/demo/src/App.jsx into focused helpers.

Why

The hub-backed model-loading path already has shared modules, but the local-folder path still leaves App.jsx responsible for IndexedDB handle persistence, folder traversal, artifact detection, tokenizer/preprocessor selection, and local URL/config assembly. That keeps the biggest block of non-UI logic in the component.

Scope

• Focus only on local-folder model support in examples/demo.
• Preserve the current UX and diagnostics.
• Keep the refactor incremental; avoid mixing unrelated UI cleanup.

Proposed Extraction

• localModelStorage helper for IndexedDB persistence/restore/clear and capability checks.
• localModelArtifacts helper for folder scan results, artifact detection, and option derivation.
• localModelUrls or equivalent helper for local blob URL/config assembly.

Acceptance Criteria

• Local-folder behavior matches current master.
• Persisted directory reconnect flow still works.
• Artifact detection and logging stay unchanged.
• examples/demo/src/App.jsx loses the bulk of local-model orchestration code.
• npm test still passes.
• examples/demo still builds successfully.

[coderabbitai]

🔗 Related PRs

#91 - Feat/demo local folder model loading [merged]

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