feat(rules): add mapMapErrorToMapBoth diagnostic

[FNDEVVE]

Adds the mapMapErrorToMapBoth diagnostic (TS377132, group style, v3+v4) for issue #628.

Transforming both channels with two adjacent combinators — Effect.map + Effect.mapError in either order — is exactly what Effect.mapBoth({ onSuccess, onFailure }) does in one step. The rule matches direct adjacency in pipe/pipeable chains (via checker symbol resolution, mirroring effectMapFlatten) plus the nested data-first shapes map(mapError(eff, g), f) and mapError(map(eff, f), g). Since the channels are independent, the rewrite is always behavior-preserving. Non-adjacent pairs stay silent.

// Before
const isPositive = fetchCount.pipe(
  Effect.map((n) => n > 0),
  Effect.mapError((message) => new TaskError({ message }))
)
// TS377132: `Effect.mapBoth` expresses these failure and success transformations more directly than adjacent `Effect.map` and `Effect.mapError`. effect(mapMapErrorToMapBoth)

// After
const isPositive = fetchCount.pipe(
  Effect.mapBoth({
    onSuccess: (n) => n > 0,
    onFailure: (message) => new TaskError({ message })
  })
)

Closes #628.

Verification

• go test ./internal/rules: pass (incl. TestRuleDocs/TestMetadataJSON/TestReadmeTable)
• go test ./internal/effecttest (full package): pass — 5 diagnostics on v4 BAD cases, no collateral on existing fixtures
• pnpm lint: clean