feat(tools): per-call approval for action tools

3-way action_tool_policy (off/ask/allow). In "ask", the chat stream stays
open and the tool loop awaits approval: emits event:tool_request, the UI
shows Approve/Deny, POST /chat/approve resumes the same stream. Declined
actions return a denied result; a timeout denies.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

synapse/memory/store.py

@@ -998,9 +998,11 @@ class PersistentMemoryStore:
         "rag_min_score": 0.6,
         # Active project/workspace; "" = all documents (unscoped).
         "active_project": "",
-        # Consent gate for tools that act (web_search/fetch_url/remember). Off by
-        # default: a playbook can list them, but they only run when this is on.
-        "allow_action_tools": False,
+        # Consent policy for tools that act (web_search/fetch_url/remember):
+        #   "off"   — withheld from the model entirely (default)
+        #   "ask"   — offered, but each call waits for per-call user approval
+        #   "allow" — offered and run freely
+        "action_tool_policy": "off",
         "system_prompt": "",
         "timeout": 120,
         # How long Ollama keeps the model resident in VRAM between messages.