agents: remove the hive-level /effort control too

mara on #5034: "effort shares /models fate". The per-agent web UI no
longer sets effort: the `/effort` slash command, the effort picker,
`POST /api/effort`, `Bus::set_effort`, the `hyperhive-effort` writer,
`EFFORT_LEVELS`/`is_valid_effort` and the ACP effort-list payload are
gone, and `lib/modelEffort.ts` with them. The effort chip is
display-only and shows its source (`effort_source` in `/api/state`);
on ACP it stays hidden while the session offers no effort level.

The read side is unchanged: with no swarm value an agent runs an
existing `hyperhive-effort` file, else its agent.nix effort, else
medium. Existing files are not touched.

Refs #5034

frontend/packages/agent/src/components/StatusChips.tsx

@@ -1,7 +1,7 @@
 // <StatusChips> — the agent page's status row: the consolidated status
 // badge (alive/thinking/paused/etc., with pause/resume + cancel-turn in
-// its dropdown), the model (display-only: the swarm sets it), the effort
-// picker, and context/cost usage.
+// its dropdown), the model and effort (display-only: the swarm sets
+// them), and context/cost usage.
 // This is the concrete fix for the design guide's own named anti-example
 // (the old page's model/effort *pickers* lived in the `⋯` overflow menu
 // while the current model/effort only showed as a disconnected chip) —
@@ -14,7 +14,7 @@
 import { useRef, useState } from "preact/hooks";
 import { Badge, type BadgeTone } from "@hive/shared/badge.js";
 import { Dropdown, type DropdownOption } from "@hive/shared/dropdown.js";
-import type { ModelSource } from "../types.js";
+import type { InferenceSource } from "../types.js";
 import "./StatusChips.css";
 
 export interface StatusChipsProps {
@@ -28,10 +28,10 @@ export interface StatusChipsProps {
    * turn has completed. */
   resolvedModel?: string;
   /** Where `model` comes from (`/api/state` `model_source`). */
-  modelSource?: ModelSource;
-  effort: string;
-  availableEfforts: string[];
-  onSelectEffort: (level: string) => void;
+  modelSource?: InferenceSource;
+  /** Hidden when empty: an ACP session that offers no effort now. */
+  effort?: string | null;
+  effortSource?: InferenceSource;
   ctxLabel?: string;
   costLabel?: string;
   paused: boolean;
@@ -52,67 +52,12 @@ export interface StatusChipsProps {
   onLogout: () => Promise<void>;
 }
 
-const SOURCE_LABEL: Record<ModelSource, string> = {
+const SOURCE_LABEL: Record<InferenceSource, string> = {
   swarm: "set on the swarm",
   agent_nix: "from agent.nix",
   local_file: "from its own earlier pick",
   default: "the built-in default",
 };
-const EFFORT_DESCRIPTIONS: Record<string, string> = {
-  low: "",
-  medium: "default",
-  high: "",
-  xhigh: "",
-  max: "",
-};
-
-function Picker({
-  label,
-  value,
-  options,
-  descriptions,
-  onSelect,
-  title,
-}: {
-  label: string;
-  value: string;
-  options: string[];
-  descriptions: Record<string, string>;
-  onSelect: (v: string) => void;
-  title?: string;
-}) {
-  const [open, setOpen] = useState(false);
-  const anchorRef = useRef<HTMLDivElement>(null);
-  const dropdownOptions: DropdownOption[] = options.map((name) => ({
-    value: name,
-    label: name,
-    description: descriptions[name] || undefined,
-  }));
-  return (
-    <div class="status-chip-anchor" ref={anchorRef}>
-      <Badge
-        label={label}
-        value={value}
-        onClick={() => setOpen((o) => !o)}
-        expanded={open}
-        title={title}
-      />
-      <Dropdown
-        open={open}
-        options={dropdownOptions}
-        activeValue={value}
-        label={`select ${label}`}
-        onSelect={(v) => {
-          onSelect(v);
-          setOpen(false);
-        }}
-        onClose={() => setOpen(false)}
-        anchorRef={anchorRef}
-      />
-    </div>
-  );
-}
-
 // The consolidated alive/thinking/paused badge (mara: "why do we
 // have separate alive badge? ... it could be one badge that shows
 // thinking / idle / paused / ... with a dropdown that opens when
@@ -240,8 +185,7 @@ export function StatusChips({
   resolvedModel,
   modelSource,
   effort,
-  availableEfforts,
-  onSelectEffort,
+  effortSource,
   ctxLabel,
   costLabel,
   paused,
@@ -277,13 +221,11 @@ export function StatusChips({
             .join(" · ") || undefined
         }
       />
-      {availableEfforts.length ? (
-        <Picker
+      {effort ? (
+        <Badge
           label="effort"
           value={effort}
-          options={availableEfforts}
-          descriptions={EFFORT_DESCRIPTIONS}
-          onSelect={onSelectEffort}
+          title={effortSource ? SOURCE_LABEL[effortSource] : undefined}
         />
       ) : null}
       {ctxLabel ? (