feat(home): opencode module — link config/opencode → ~/.config/opencode

Adds metacfg.cli-apps.opencode (default enabled) which mounts the
in-repo opencode config (provider list, web-search skill) via
xdg.configFile, so all hosts pick it up automatically.

config/opencode/config.json

@@ -0,0 +1,39 @@
+{
+  "$schema": "https://opencode.ai/config.json",
+  "provider": {
+    "halo-8001": {
+      "npm": "@ai-sdk/openai-compatible",
+      "name": "Halo (8001)",
+      "options": {
+        "baseURL": "http://halo.fritz.box:8001/v1"
+      },
+      "models": {
+        "unsloth/Qwen3.6-35B-A3B-GGUF:UD-Q8_K_XL": { "name" : "halo 8001" }
+      }
+    },
+    "halo-8000": {
+      "npm": "@ai-sdk/openai-compatible",
+      "name": "Halo (8000)",
+      "options": {
+        "baseURL": "http://halo.fritz.box:8000/v1"
+      },
+      "models": {
+        "unsloth/gemma-4-26B-A4B-it-GGUF:UD-Q8_K_XL": {
+          "name": "halo 8000"
+        }
+      }
+    },
+    "lmstudio-local": {
+      "npm": "@ai-sdk/openai-compatible",
+      "name": "LM Studio (local)",
+      "options": {
+        "baseURL": "http://127.0.0.1:1234/v1"
+      },
+      "models": {
+        "qwen3-coder-30b-a3b-instruct-mlx@6bit": {
+          "name": "qwen3-coder-30b-a3b-instruct-mlx@6bit"
+        }
+      }
+    }
+  }
+}