feat(anti-slop): add no-reduce-accumulator-copy rule

[howmanysmall]

Summary

Vendors a new anti-slop rule that flags reducers copying their accumulator each iteration, and wires it through the plugin, docs, and lint config.

 src/rules/anti-slop/
+├── no-reduce-accumulator-copy.ts   # flags Object.assign/Array.from/array-copy of the accumulator
 ├── no-module-mocking.ts
 └── ...
 src/utilities/
-└── ast-utilities.ts
+└── ast-utilities.ts                # + getReferencedVariable, + hasUninitializedWrite
 tests/rules/anti-slop/
+└── no-reduce-accumulator-copy.test.ts
 documentation/src/content/docs/rules/anti-slop/
+└── no-reduce-accumulator-copy.mdx

Rebases the vendored anti-slop snapshot onto upstream c44ef22 and lifts the shared resolveVariable/hasUninitializedWrite helpers out of individual rules into ast-utilities.ts, so no-module-mocking, no-widen-then-assert, and reflect-method reuse them instead of re-implementing.

Evidence

• Before: no-reduce-accumulator-copy did not exist, so the fixtures in tests/rules/anti-slop/no-reduce-accumulator-copy.test.ts could not run against a rule.
  After: nr test tests/rules/anti-slop/no-reduce-accumulator-copy.test.ts

Test Files  2 passed (2)
     Tests  72 passed (72)
Type Errors  no errors

The suite covers the positive cases (Object.assign({}, acc, …), Array.from(acc), acc.concat/slice/toReversed/… with an array initial value) plus aliases, shadowed globals, non-array initial values, and nested functions.

Merge Danger

Door: two-way — the rule is additive and revertable.

Blast Radius: consumers.

Adding small-rules/no-reduce-accumulator-copy: error to the default oxlint config means existing reduce-copy code will start erroring on upgrade; the rule only fires when the reducer's initial value is provably an array, or the copy target is a fresh object literal.

[github-actions]

React Doctor found no new issues. 🎉

_{Reviewed by React Doctor for commit d8ebedb.}

[github-actions]

Bundle size

Artifact	Base	Pull request	Change
dist/index.js	486.04 kB	489.01 kB	+2.97 kB (+0.61%)

_{Raw, uncompressed bytes from the minified prepublishOnly build. Measured for commit d8ebedb against base 386995e.}