feat(impact): blast radius — reverse-dependency traversal (5.3)

[officialCodeWork]

What

TRACKER step 5.3 — Blast radius (reverse traversal) (failure mode F2).

blastRadius(graph, target) in @coderadar/core: everything that depends on a node, so a change can be reviewed for impact. It's a dependency-direction-aware reverse BFS — dependencyOf() maps each edge kind to which endpoint is the resource and which depends on it, so impact propagates the correct way regardless of edge direction (a data source's consumers are reached through both incoming fetches-from and outgoing provides-data). Journey edges (handles/triggers/navigates-to/exits-app/enters-at) are behaviour, not data/render dependencies, so they don't propagate.

• Resolves a target by node id, component name, API endpoint, state name, or route path.
• Returns ImpactNode[] — { node, relation, distance }, nearest-first — always high-confidence (deterministic traversal).
• Wired into the context bundle's blastRadius section (compact Name@file:line labels).
• New CLI impact <node> command, -d/--depth cap, indented by distance.

Accept

c1-shared-datatable golden gains a blast block:

• changing the shared DataTable definition → both page instances (d1) + both pages that render them (d2);
• changing /api/users → every consumer (the fetching page + the table instance it feeds), with an over-reach guard forbidding InvoicesPage / /api/invoices.

New GoldenBlast type + blast check kind in the eval harness.

Verification

• 6 packages build/typecheck clean
• unit tests: 170 pass (core 46 incl. 5 new blast tests, agent-sdk 14, vision 3, parser 107)
• eval: 258 pass · 0 fail · 0 xfail — precision/recall 1.000, high-conf 1.000, poison 0.000, gate OK

🤖 Generated with Claude Code