fix(react-doctor): correctly exclude test files from scoring

The intended test-file ignore in react-doctor.config.json was never
applied: react-doctor's config precedence reads the "reactDoctor" key
in package.json (which had no ignore), shadowing the config file. On
top of that, react-doctor 0.4.0's ignore.files matcher is broken — any
non-empty value collapses scan scope and drops real product files, not
just tests.

Consolidate to a single canonical doctor.config.json using
ignore.overrides (which works correctly): only test files are excluded
while all product code is still scored. Remove the shadowing
package.json key and the dead react-doctor.config.json.

Product-code baseline is 55 (92 errors, 515 warnings, 118 files).

doctor.config.json

@@ -0,0 +1,6 @@
+{
+  "diff": false,
+  "ignore": {
+    "overrides": [{ "files": ["**/__tests__/**", "**/*.test.*"] }]
+  }
+}

package.json

@@ -259,8 +259,5 @@
     "commitizen": {
       "path": "./node_modules/cz-conventional-changelog"
     }
-  },
-  "reactDoctor": {
-    "diff": false
   }
 }

react-doctor.config.json

@@ -1,6 +0,0 @@
-{
-  "diff": false,
-  "ignore": {
-    "files": ["**/__tests__/**", "**/*.test.*"]
-  }
-}