fix(boundaries): allow feature-to-feature imports of public exports

turbo.json's boundary config already allows `feature -> feature`, and
the cross-feature event system depends on it — a consumer must import
the publisher's event contract from `@repo/<publisher>`. But the ESLint
boundaries config, ADR-010, and AGENTS.md still declared
`feature -> [core, tooling]`, contradicting turbo.json and the shipped
code (marketing-pages imports @repo/auth).

Align all three to turbo.json: a feature may import another feature's
published public exports. Internals stay sealed by the `exports` map,
and cross-feature behaviour still flows through IEventBus.

packages/core-eslint/base.js

@@ -96,7 +96,7 @@ export default [
               from: "app",
               allow: ["app", "core", "core-composition", "feature", "tooling"],
             },
-            { from: "feature", allow: ["core", "tooling"] },
+            { from: "feature", allow: ["core", "feature", "tooling"] },
             { from: "core", allow: ["core", "tooling"] },
             { from: "core-composition", allow: ["core", "feature", "tooling"] },
             { from: "tooling", allow: ["tooling"] },