agent-loop: Skald adapters behind the crate traits (phase 1)

New skald-core::loop_adapters module — implements the agent-loop trait
surface over existing infrastructure, unused by the current loop (wired
in phase 2):

- SqliteHistory: HistoryStore over chat_sessions_stack/chat_history/
  chat_llm_tools/chat_summaries, no schema change; CallState maps 1:1 on
  the existing status strings; wire call ids synthesized as tc_{id}
- SkaldSelector: ModelSelector over LlmManager with the agent's strength
  captured per-turn (D14); DtlMode → ToolRendering mapping (D15)
- SkaldActivationSource + SkaldToolActivator: DTL catalog + persistence
  (activated_tools, anchored at the triggering message) behind the
  crate's protocol traits; unifies the grants/persistence split
- ApprovalGate: port of run_approval_gate (pre-approved, engine, fs
  fast-path, auto-deny, AwaitingHuman + block on human); a closed human
  channel maps to the new GateDecision::Suspend in agent-loop
- SkaldToolSet + CoreToolBridge/McpToolBridge: core-api and MCP tools
  run inside the crate's kernel (execution bridged, execute_cmd keeps
  its teardown; D7 MarkInterrupted for shell)
- agent-loop: re-export async_trait at root; EventSink::new made public

17 adapter tests green (temp-DB integration); full workspace suite green
(pre-existing honcho-client doc-test failure untouched: missing dev-deps).

Cargo.lock

@@ -4242,6 +4242,7 @@ dependencies = [
  "rand 0.10.1",
  "regex",
  "reqwest 0.13.4",
+ "rustls",
  "serde",
  "serde_json",
  "serde_yaml",