Add Qwen3-Coder-Next model cards (#1367)

## Motivation

Qwen3-Coder-Next just dropped on mlx-community in several quantizations.
It's an 80B MoE model (Qwen3NextForCausalLM) which we already have
tensor parallelism support for via QwenShardingStrategy — just needs
model cards.

## Changes

Added model cards for all 5 available quantizations:
- `mlx-community/Qwen3-Coder-Next-4bit` (~46GB)
- `mlx-community/Qwen3-Coder-Next-5bit` (~58GB)
- `mlx-community/Qwen3-Coder-Next-6bit` (~69GB)
- `mlx-community/Qwen3-Coder-Next-8bit` (~89GB)
- `mlx-community/Qwen3-Coder-Next-bf16` (~158GB)

All with `supports_tensor = true` since the architecture is already
supported.

## Why It Works

`Qwen3NextForCausalLM` is already handled by QwenShardingStrategy in
auto_parallel.py and is in the supports_tensor allowlist in
model_cards.py. No code changes needed — just the TOML card files.

## Test Plan

### Manual Testing
<!-- n/a - model card addition only -->

### Automated Testing
- `basedpyright` — 0 errors
- `ruff check` — passes
- `nix fmt` — no changes
- `pytest` — 173 passed, 1 skipped


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

Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

resources/inference_model_cards/mlx-community--Qwen3-Coder-Next-4bit.toml

@@ -0,0 +1,8 @@
+model_id = "mlx-community/Qwen3-Coder-Next-4bit"
+n_layers = 48
+hidden_size = 2048
+supports_tensor = true
+tasks = ["TextGeneration"]
+
+[storage_size]
+in_bytes = 45644286500

resources/inference_model_cards/mlx-community--Qwen3-Coder-Next-5bit.toml

@@ -0,0 +1,8 @@
+model_id = "mlx-community/Qwen3-Coder-Next-5bit"
+n_layers = 48
+hidden_size = 2048
+supports_tensor = true
+tasks = ["TextGeneration"]
+
+[storage_size]
+in_bytes = 57657697020

resources/inference_model_cards/mlx-community--Qwen3-Coder-Next-6bit.toml

@@ -0,0 +1,8 @@
+model_id = "mlx-community/Qwen3-Coder-Next-6bit"
+n_layers = 48
+hidden_size = 2048
+supports_tensor = true
+tasks = ["TextGeneration"]
+
+[storage_size]
+in_bytes = 68899327465

resources/inference_model_cards/mlx-community--Qwen3-Coder-Next-8bit.toml

@@ -0,0 +1,8 @@
+model_id = "mlx-community/Qwen3-Coder-Next-8bit"
+n_layers = 48
+hidden_size = 2048
+supports_tensor = true
+tasks = ["TextGeneration"]
+
+[storage_size]
+in_bytes = 89357758772

resources/inference_model_cards/mlx-community--Qwen3-Coder-Next-bf16.toml

@@ -0,0 +1,8 @@
+model_id = "mlx-community/Qwen3-Coder-Next-bf16"
+n_layers = 48
+hidden_size = 2048
+supports_tensor = true
+tasks = ["TextGeneration"]
+
+[storage_size]
+in_bytes = 157548627945