Add Torque.get_many_defaults/3 for 0.1.9

Variant of get_many_nil/2 that takes %{path => default} and returns
%{path => value_or_default}. Saves callers from the awkward two-call
pattern:

  paths = Map.keys(defaults)
  values = Torque.get_many_nil(doc, paths)
  Enum.zip(paths, values)
  |> Map.new(fn {p, nil} -> {p, Map.get(defaults, p)}; pv -> pv end)

Now a single call:

  Torque.get_many_defaults(doc, %{
    "/user/id" => 0,
    "/user/name" => "anonymous",
    "/created_at" => nil
  })

Returns a same-shape map with parsed values, falling back to the
provided defaults for missing/null fields. Same nil/missing
indistinguishability semantics as get_many_nil/2.

Pure-Elixir wrapper around the existing NIF (get_many_nil/2); no
new Rust code, no NIF dispatch overhead beyond the one
get_many_nil call. Has an embedded doctest exercised by the test
suite.

D1's two other plan items resolved on inspection:

- 'aarch64 baseline variant in release matrix' -- aarch64 v8 is
  universal across consumer CPUs, no v2 distinction needed. The
  matrix already ships aarch64-apple-darwin + aarch64-linux-gnu.

- 'property test for float round-trip precision' -- already
  covered by test/property_test.exs (35 properties, 626 lines)
  with a json_scalar generator that includes float(-1000..1000),
  encoded/decoded through the round-trip suite.

README and mix.exs version both bumped to 0.1.9.

Author: lpgauth

README.md

@@ -20,7 +20,7 @@ Add to your `mix.exs`:
 ```elixir
 def deps do
   [
-    {:torque, "~> 0.1.8"}
+    {:torque, "~> 0.1.9"}
   ]
 end
 ```

lib/torque.ex

@@ -298,6 +298,47 @@ defmodule Torque do
     Torque.Native.get_many_nil(doc, paths)
   end
 
+  @doc """
+  Extracts multiple values from a parsed document with per-path defaults.
+
+  Takes a map of `%{path => default}` and returns a map of the same shape
+  where each value is either the parsed value or the supplied default (if
+  the path is missing).
+
+  More ergonomic than the two-call `get_many_nil/2` + `Enum.map` pattern
+  when consumers need defaults at the call site.
+
+  Equivalent to:
+
+      get_many_nil(doc, Map.keys(defaults))
+      |> then(&Enum.zip(Map.keys(defaults), &1))
+      |> Map.new(fn {p, nil} -> {p, Map.get(defaults, p)}; pv -> pv end)
+
+  Note: a parsed JSON `null` at the path is indistinguishable from a missing
+  field (same as `get_many_nil/2`) — both substitute the default.
+
+  ## Examples
+
+      iex> {:ok, doc} = Torque.parse(~s({"a":1,"b":null}))
+      iex> Torque.get_many_defaults(doc, %{"/a" => 0, "/b" => 0, "/c" => "missing"})
+      %{"/a" => 1, "/b" => 0, "/c" => "missing"}
+  """
+  @doc group: :parse_get
+  @spec get_many_defaults(reference(), %{binary() => term()}) ::
+          %{binary() => term()}
+  def get_many_defaults(doc, defaults)
+      when is_reference(doc) and is_map(defaults) do
+    paths = Map.keys(defaults)
+    values = Torque.Native.get_many_nil(doc, paths)
+
+    paths
+    |> Enum.zip(values)
+    |> Map.new(fn
+      {path, nil} -> {path, Map.get(defaults, path)}
+      pv -> pv
+    end)
+  end
+
   @doc """
   Returns the length of an array at the given JSON Pointer path, or `nil` if
   the path does not exist or does not point to an array.

mix.exs

@@ -1,7 +1,7 @@
 defmodule Torque.MixProject do
   use Mix.Project
 
-  @version "0.1.8"
+  @version "0.1.9"
   @source_url "https://github.com/lpgauth/torque"
 
   def project do