fix: resolve teardown timeout before registration to prevent orphaned state

If resolve_teardown_timeout() raised after launch_consolidated()/register_agent()
returned, the teardown callback was never registered, leaving the bottle
registered with no cleanup path. Resolve the timeout into a local variable
before the registration call so any failure aborts before the bottle exists.

Add tests covering OrchestratorConfigStore, resolve_teardown_timeout priority
ordering (env > db > default), and the source-order invariant that the resolver
runs before registration in all three backends.

bot_bottle/backend/macos_container/launch.py

@@ -143,6 +143,7 @@ def launch(
         token_values = egress_resolve_token_values(
             plan.egress_plan.token_env_map, effective_env,
         )
+        teardown_timeout = resolve_teardown_timeout()
         ctx = register_agent(
             plan.egress_plan,
             plan.git_gate_plan,
@@ -154,7 +155,7 @@ def launch(
         stack.callback(
             teardown_consolidated, ctx.bottle_id,
             orchestrator_url=ctx.orchestrator_url,
-            timeout=resolve_teardown_timeout(),
+            timeout=teardown_timeout,
         )
         info(
             f"agent {plan.container_name} registered "