fix(resolution): Svelte/Vue component resolvers get the #764 ambiguity rule (#814)

Follow-up to #813: the React resolver's blind components[0] fallback was
the demonstrated wrong-edge source, but the Svelte and Vue resolvers had
the same flaw in their own shape:

- svelte: resolveComponent fell back to components[0] across the whole
  repo when no same-directory match existed — an arbitrary pick among
  same-named components in a multi-app monorepo.
- vue: resolveComponent returned the FIRST basename-matching .vue file
  found anywhere in the tree; its same-directory pass below was
  unreachable dead code. apps/a/Button.vue vs apps/b/Button.vue was a
  file-enumeration-order coin flip.

Both now follow the #764 rule: same-directory first, otherwise only an
UNAMBIGUOUS name resolves — ambiguity falls through to the name-matcher's
proximity scoring instead of guessing.

Safety: zero-delta A/B on the README's own framework benchmark repos
(sveltejs/realworld — the 100% Svelte coverage repo — and nuxt/movies,
93.5% Vue coverage) plus the excalidraw control: node counts identical,
zero calls or references edges changed. Single-app repos have unique
component names, so the rule only bites where the old behavior was
already a coin flip. Full suite 1398 passed.

Also verified the #813 per-definition tool grouping is language-agnostic
(probed Go same-named functions across packages — grouped identically to
the TS fixture).

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/resolution/frameworks/svelte.ts

@@ -220,7 +220,11 @@ function resolveComponent(
   const sameDir = components.filter((n) => n.filePath.startsWith(fromDir));
   if (sameDir.length > 0) return sameDir[0]!.id;
 
-  return components[0]!.id;
+  // No positional signal: only an UNAMBIGUOUS name may resolve — picking
+  // components[0] chose an arbitrary same-named component in a multi-app
+  // monorepo (#764). Ambiguity falls through to the name-matcher, whose
+  // proximity scoring decides.
+  return components.length === 1 ? components[0]!.id : null;
 }
 
 /**