fix(haskell): render any-type as Aeson Value instead of Maybe Text

[schani]

Bug

The Haskell renderer mapped quicktype's "any" type to Maybe Text, which
only decodes JSON strings or null. Any schema resolving to any-type —
including a bare empty schema {} and nested cases like
additionalProperties: true — generated Haskell code that fails to decode
valid JSON values that aren't strings or null (numbers, booleans, objects,
arrays).

Repro:

echo '{}' > empty.schema
node dist/index.js --lang haskell --src-lang schema empty.schema

Before:

type Empty = Maybe Text

After:

type Empty = Value

Root cause

HaskellRenderer.ts's haskellType mapped anyType to Maybe Text
instead of a type that can hold arbitrary JSON. TypeScript emits any,
Dart emits dynamic, and Elm already handles this correctly by emitting
Jdec.value (Elm's arbitrary-JSON type). Aeson's Value is the Haskell
equivalent — it has identity ToJSON/FromJSON instances and can
represent any JSON value.

Fix

In packages/quicktype-core/src/language/Haskell/HaskellRenderer.ts,
anyType now renders as Value (from Data.Aeson, already imported)
instead of Maybe Text.

Test coverage

• Enabled the existing any.schema JSON Schema fixture for the Haskell
  target (previously in skipSchema).
• Extended test/inputs/schema/any.schema to add an additionalProperties: true property alongside the existing bare {} property.
• Extended the any.N.json samples to include non-string any-typed values
  (numbers, objects, arrays, booleans, null) that would fail to round-trip
  under the old Maybe Text mapping.

Verification

• npm run build passes.
• Re-ran the issue's repro command: output changed from type Empty = Maybe Text to type Empty = Value.
• Confirmed the extended any.schema fixture would fail on the unfixed
  renderer (a Maybe Text field cannot decode a JSON number/object/array)
  and generates correct-looking Aeson-based code after the fix.
• This sandbox has no GHC/stack toolchain available, so the Haskell fixture
  test (QUICKTEST=true FIXTURE=schema-haskell script/test) could not be
  compiled and run locally; CI will validate the generated Haskell actually
  compiles and round-trips correctly.

Fixes #2005

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