feat(trace): render per-instance attribution for shared components

[officialCodeWork]

Summary

The definition-level trace of a shared component (the headline C1 case, e.g. DataTable) surfaced no data sources — confusing, because such components own no data of their own; each render site feeds them different data via props. This adds per-instance attribution so trace shows which endpoint reaches which render site.

Changes

• core (packages/core/src/query.ts): add InstanceAttribution and an optional Lineage.perInstance. traceLineage now finds the parents that render the target and, when a component is shared (≥2 parents), attributes each parent's reachable data sources (minus the component's own) to that render site. Non-shared components are unchanged — perInstance is absent.
• cli (packages/cli/src/index.ts): render a per instance block showing each Component@Parent site and its distinct endpoints. Definition-level output is preserved.
• eval: add the c1-shared-datatable fixture (UsersPage → /api/users, InvoicesPage → /api/invoices, both rendering DataTable).

Verification

node packages/cli/dist/index.js scan eval/fixtures/c1-shared-datatable/app -o /tmp/c1.graph.json
node packages/cli/dist/index.js trace DataTable -g /tmp/c1.graph.json

DataTable  (DataTable.tsx:11)
  per instance:
    DataTable@InvoicesPage  (InvoicesPage.tsx:5)
      → GET /api/invoices  (InvoicesPage.tsx:9)
    DataTable@UsersPage  (UsersPage.tsx:5)
      → GET /api/users  (UsersPage.tsx:9)

pnpm build and pnpm typecheck pass across all three packages. trace UsersPage (non-shared) still prints the full definition-level output with no per-instance block.

Note

Per-instance attribution is "data reachable from the rendering parent," not "data statically proven to flow into this component's props." For this fixture they coincide exactly; resolving prop-level dataflow (cf. build/phase-2/step-2.2-prop-flow) would tighten it further.

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