fix(submitter): submit_batch/2 crashed on every call (MatchError) (#48)

## Bug

`FeedbackATron.Submitter.submit_batch/2` — a public API — raised
`MatchError` on **every** call with a non-empty issue list, crashing the
`Submitter` GenServer.

`handle_call({:submit_batch, ...})` maps over issues and matches the
inner `handle_call({:submit, ...})` against a bare `{:ok, id, result}`.
But `handle_call` returns a GenServer **`{:reply, {:ok, id, result},
state}` 3-tuple** — so the match always failed.

Found while running the suite during pipeline work (the existing test
`submitter_test.exs` `submit_batch/2 batch submission processes multiple
issues` was red).

## Fix

Destructure the reply payload: `{:reply, {:ok, id, result}, _new_state}
= handle_call(...)`.

## Verification

Previously-failing test now passes; **full suite green (139 tests, 0
failures)**.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>

Author: hyperpolymath

elixir-mcp/lib/feedback_a_tron/submitter.ex

@@ -119,7 +119,9 @@ defmodule FeedbackATron.Submitter do
   @impl true
   def handle_call({:submit_batch, issues, opts}, _from, state) do
     results = Enum.map(issues, fn issue ->
-      {:ok, id, result} = handle_call({:submit, issue, opts}, nil, state)
+      # handle_call({:submit, ...}) returns a GenServer {:reply, payload, state}
+      # 3-tuple; destructure the reply payload, not a bare {:ok, id, result}.
+      {:reply, {:ok, id, result}, _new_state} = handle_call({:submit, issue, opts}, nil, state)
       {id, result}
     end)
     {:reply, {:ok, results}, state}