remove otel.metricIntervalMs and the host-level otel.debug

Both are ignored with a warning through the same shim, now
nix/host-modules/hive-options-removed.nix.

- otel.metricIntervalMs: claude in every agent and hive-c0re's
  container-resource exporter run at the 60s default. The agent-level
  services.hyperhive.agent.otel.metricIntervalMs, set only by the meta
  render, goes too (warning shim in nix/agent-modules/otel-removed.nix).
- otel.debug: services.hyperhive.agent.otel.debug stays, documented and
  set in an agent's own config; the meta render no longer emits it.

nix/agent-modules/otel-removed.nix

@@ -0,0 +1,27 @@
+# Removal shim for `services.hyperhive.agent.otel.metricIntervalMs`.
+#
+# A definition is ignored and produces a warning, so an agent config, or a
+# meta flake rendered before the option went, keeps evaluating. claude runs
+# at the OTEL SDK's default export cadence.
+#
+# Self-contained and deletable: one file to remove when the deprecation
+# window closes.
+{ lib, config, ... }:
+let
+  value = config.services.hyperhive.agent.otel.metricIntervalMs;
+in
+{
+  options.services.hyperhive.agent.otel.metricIntervalMs = lib.mkOption {
+    type = lib.types.nullOr lib.types.ints.positive;
+    default = null;
+    visible = false;
+    internal = true;
+    description = "Removed and ignored. `null` is \"not set\".";
+  };
+
+  config.warnings = lib.optional (value != null) ''
+    services.hyperhive.agent.otel.metricIntervalMs is removed and ignored:
+    claude exports metrics at the SDK default of 60 seconds. Remove this
+    setting.
+  '';
+}