feat: check OLLAMA_HOST reachability before starting translationv1.6

Non-blocking QThread check hits /api/tags on the resolved ollama host
before launching TranslationWorker. Shows QMessageBox.warning() if
unreachable; proceeds silently if reachable. Adds ollama_host field to
Config with env-var fallback to http://localhost:11434.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

1 files changed, 19 insertions, 0 deletions

diff --git a/workers/ollama_check_worker.py b/workers/ollama_check_worker.py
new file mode 100644
index 0000000..5f47492
--- /dev/null
+++ b/workers/ollama_check_worker.py
@@ -0,0 +1,19 @@
+from __future__ import annotations
+import urllib.request
+from PyQt6.QtCore import QThread, pyqtSignal
+
+
+class OllamaCheckWorker(QThread):
+    reachable = pyqtSignal(bool, str)  # (ok, url_tried)
+
+    def __init__(self, host_url: str, timeout: int = 4, parent=None):
+        super().__init__(parent)
+        self._url = host_url.rstrip("/") + "/api/tags"
+        self._timeout = timeout
+
+    def run(self):
+        try:
+            urllib.request.urlopen(self._url, timeout=self._timeout)
+            self.reachable.emit(True, self._url)
+        except Exception:
+            self.reachable.emit(False, self._url)