First pass at uniformed types, specs and docs

- spec public functions (skipping controllers, views, live views and
components)
- use types instead of explanations in docs
- remove redundant docs
- fix typos

lib/sqlite_vec/ecto/float32.ex

@@ -4,16 +4,24 @@ defmodule SqliteVec.Ecto.Float32 do
   """
   use Ecto.Type
 
+  @impl true
+  @spec type() :: :binary
   def type, do: :binary
 
+  @impl true
+  @spec cast(any()) :: {:ok, SqliteVec.Float32.t()}
   def cast(value) do
     {:ok, SqliteVec.Float32.new(value)}
   end
 
+  @impl true
+  @spec load(binary()) :: {:ok, SqliteVec.Float32.t()}
   def load(data) do
     {:ok, SqliteVec.Float32.from_binary(data)}
   end
 
+  @impl true
+  @spec dump(SqliteVec.Float32.t()) :: {:ok, binary()} | :error
   def dump(%SqliteVec.Float32{} = vector) do
     {:ok, SqliteVec.Float32.to_binary(vector)}
   end

lib/sqlite_vec/ecto/query.ex

@@ -75,6 +75,9 @@ defmodule SqliteVec.Ecto.Query do
     end
   end
 
+  @doc """
+  Matches a vector against a virtual table using the `match` operator.
+  """
   defmacro vec_match(a, b) do
     quote do
       fragment("? match ?", unquote(a), unquote(b))