feat(openrouter): add qwen3.6-plus free model configuration

- Add Qwen3.6 Plus (free) provider configuration
- $0 pricing with 1M context window
- Multimodal input support (text, image, video)
- Full capabilities: reasoning, tool calls, structured output
- Attachment enabled for vision modality

Author: cantalupo555

providers/openrouter/models/qwen/qwen3.6-plus:free.toml

@@ -0,0 +1,22 @@
+name = "Qwen3.6 Plus (free)"
+family = "qwen"
+release_date = "2026-04-02"
+last_updated = "2026-04-02"
+attachment = true
+reasoning = true
+temperature = true
+tool_call = true
+structured_output = true
+open_weights = false
+
+[cost]
+input = 0.00
+output = 0.00
+
+[limit]
+context = 1_000_000
+output = 65_536
+
+[modalities]
+input = ["text", "image", "video"]
+output = ["text"]