fix(agent): detect repeated tool call loops and make max_iterations configurable

Local LLMs often get stuck calling the same tool repeatedly because they
lack the sophistication to synthesize results. The agent loop had no
safeguard — it re-executed whatever the model requested up to 10 times.

Add fingerprint-based loop detection: if the same tool+args combination
repeats 3 consecutive times, break the loop and return the last results.
Also add agents.max_iterations to the config schema so the iteration
limit is user-configurable (default: 10).

src/daemon/routing.ts

@@ -134,6 +134,7 @@ export function createMessageRouter(deps: {
         primaryTier: effectiveTier,
         delegation: delegationConfig,
         maxDelegationDepth: deps.config.agents.max_delegation_depth ?? 3,
+        maxIterations: deps.config.agents.max_iterations,
         compaction: deps.config.compaction.enabled ? {
           thresholdPct: deps.config.compaction.threshold_pct,
           keepTurns: deps.config.compaction.keep_turns,