[BUG] Symbol search returns CUSTOM_SCRAPER without provider code — quote price missing for custom-provider assets

Summary

When selecting an existing asset backed by a custom scraper provider in Add Activity → symbol search, the UI shows name and currency but no live price. Quote resolution fails because search returns providerId: "CUSTOM_SCRAPER" instead of CUSTOM:<code>.

Root cause

Custom-provider assets are stored correctly in provider_config:

{
  "preferred_provider": "CUSTOM_SCRAPER",
  "custom_provider_code": "moe"
}

Symbol search maps existing assets via asset.preferred_provider(), which returns only "CUSTOM_SCRAPER".

Add Activity then calls resolve-currency with that value. Resolution only works when the provider id includes the custom code:

The frontend already uses CUSTOM:<code> elsewhere (asset edit, serializeProviderConfig / parsePreferredProvider). Symbol search is the missing piece.

Scope

Affected: Any asset using a custom scraper provider (custom_provider_code set).

Not affected (as far as we know): Holdings / latest quotes — QuoteContext passes custom_provider_code separately from provider_config. Yahoo, Finnhub, etc. are unaffected.

Related surfaces to sanity-check after fix:

• Add Activity symbol search + price preview
• Any API/UI that exposes providerId from preferred_provider() alone
• Catalog → create asset flow (storage format is fine; resolution wire format matters)

Proposed fix

Add a helper on Asset, e.g. symbol_resolution_provider_id():

• If preferred_provider == "CUSTOM_SCRAPER" and custom_provider_code is set → return CUSTOM:{code}
• Otherwise → return preferred_provider()

Use it in asset_to_quote_summary() (symbol search) for providerId and dataSource instead of bare preferred_provider().

Files:

• crates/core/src/assets/assets_model.rs — new helper
• crates/core/src/quotes/service.rs — use in search result mapping
• Unit tests for custom scraper + non-custom (e.g. YAHOO)