Set the search summary model from the settings panel

Summarizing web search results falls back to DEFAULT_MODEL, so a local Ollama
model ends up doing it and the call can fail — which surfaces only as
"保存できる要約なし" in the chat. Make SEARCH_SUMMARY_MODEL settable at runtime:
add it to the settings allowlist and read it from os.environ on each call
(knowledge._summary_model), the way LOCAL_KB_EMBEDDING_MODEL already works.
Importing it as a config constant would keep the old value until a restart.

Show the current value of the settings that are not secrets. A model name
rendered as ••••qwen3 gives no way to tell what is in effect, so the store now
marks those keys (NON_SECRET_KEYS) and returns them unmasked; the API field is
renamed masked -> display_value and carries a secret flag that the panel uses
to pick the input type, replacing the list it kept on its own side.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

backend/app/core/settings_store.py

@@ -16,8 +16,18 @@ CONFIGURABLE_KEYS = [
     "OLLAMA_API_BASE",
     "TAVILY_API_KEY",
     "LOCAL_KB_EMBEDDING_MODEL",
+    "SEARCH_SUMMARY_MODEL",
 ]
 
+# 秘匿情報ではないキー。値をマスクせずそのまま返し、GUIでも通常のテキスト入力として扱う。
+# モデル名やURLは「今どれが効いているか」が見えないと設定しづらいため。
+NON_SECRET_KEYS = {
+    "AWS_REGION_NAME",
+    "OLLAMA_API_BASE",
+    "LOCAL_KB_EMBEDDING_MODEL",
+    "SEARCH_SUMMARY_MODEL",
+}
+
 # .env由来の起動時の値のスナップショット。clear() で戻す先として使う。
 _env_defaults: dict[str, str | None] = {}
 _snapshot_taken = False
@@ -47,15 +57,18 @@ def load_into_env(db: DBSession) -> None:
 
 
 def list_masked(db: DBSession) -> list[dict]:
+    """GUI設定画面に出す一覧。秘匿キーの値はマスクし、そうでないキーは現在値をそのまま見せる。"""
     _ensure_snapshot()
     saved = {row.key: row.value for row in db.query(AppSetting).all()}
     result = []
     for key in CONFIGURABLE_KEYS:
         current = os.environ.get(key)
+        secret = key not in NON_SECRET_KEYS
         result.append({
             "key": key,
             "is_set": bool(current),
-            "masked": _mask(current) if current else None,
+            "display_value": (_mask(current) if secret else current) if current else None,
+            "secret": secret,
             "overridden": key in saved,
         })
     return result