swarm-ui: sortable + filterable table columns

hyperhive#4020, mara. TableColumn gets two new optional extractors,
each one the whole signal for its capability (mara: 'why separate
selector and flag?' — dropped the sortable/filterable booleans that
would've said the same thing twice and could disagree with the
extractor's presence):

- sortBy: (row) => string | number — column is click-to-sort iff
  present. Table owns the sort state (one active column, header click
  cycles none -> ascending -> descending), since a rendered cell often
  isn't the sortable value itself (e.g. AgentsPage's status column
  renders a Badge, not a plain string).
- filterValue: (row) => string — column is filterable iff present. A
  text input row under the headers, substring match case-insensitive.

Client-side only, no backend change - every consuming page already
fetches its full row set. Wired into AgentsPage and HivesPage, the two
pages with a real per-row Table. Left IssueReportPage alone (already
has its own purpose-built sort + label/hide-blocked filters, predates
this and covers its own domain better than a generic per-column text
filter would) and JobsPage alone (renders an indented state tree via
JobqGraph, no column table at all despite what my original scoping
comment assumed).

Verified: typecheck + build clean, nix fmt clean, static render of the
actual built CSS confirms the new sort-header + filter-row markup
doesn't break table layout.

frontend/packages/swarm-ui/src/pages/AgentsPage.tsx

@@ -207,8 +207,20 @@ export function AgentsPage() {
   }
 
   const columns: TableColumn<AgentRow>[] = [
-    { key: "name", header: "name", render: (a) => a.name },
-    { key: "hive", header: "hive", render: (a) => a.hive ?? "—" },
+    {
+      key: "name",
+      header: "name",
+      render: (a) => a.name,
+      sortBy: (a) => a.name,
+      filterValue: (a) => a.name,
+    },
+    {
+      key: "hive",
+      header: "hive",
+      render: (a) => a.hive ?? "—",
+      sortBy: (a) => a.hive ?? "",
+      filterValue: (a) => a.hive ?? "",
+    },
     {
       key: "status",
       header: "status",
@@ -217,6 +229,8 @@ export function AgentsPage() {
       // stuffed a full sentence into a pill meant for a short discrete
       // label and blew the row out (mara: "looks messy"). That string
       // now lives in its own "message" column below.
+      sortBy: (a) => FRESHNESS[a.freshness].label,
+      filterValue: (a) => FRESHNESS[a.freshness].label,
       render: (a) => {
         const { tone, label } = FRESHNESS[a.freshness];
         return (
@@ -252,6 +266,7 @@ export function AgentsPage() {
       // `status_text: null` (the wire contract's own rule), so a stopped
       // agent just shows an em dash here rather than a stale message.
       render: (a) => a.snapshot?.status_text ?? "—",
+      filterValue: (a) => a.snapshot?.status_text ?? "",
     },
     {
       key: "wanted",
@@ -261,6 +276,8 @@ export function AgentsPage() {
       // control" shape (see its header comment, which names pause/resume
       // as the exact motivating case), not a separate status chip next
       // to a separate button.
+      sortBy: (a) => a.wanted ?? "",
+      filterValue: (a) => a.wanted ?? "no declaration",
       render: (a) => {
         const pending = pendingAgents.has(a.name);
         const impliedCurrent =
@@ -295,6 +312,8 @@ export function AgentsPage() {
     {
       key: "config-pr",
       header: "config PR",
+      sortBy: (a) => a.config_pr?.pr_number ?? 0,
+      filterValue: (a) => (a.config_pr ? `#${a.config_pr.pr_number}` : ""),
       render: (a) =>
         a.config_pr ? (
           <Badge

frontend/packages/swarm-ui/src/pages/HivesPage.tsx

@@ -49,7 +49,13 @@ const FRESHNESS: Record<Freshness, { tone: BadgeTone; label: string }> = {
 };
 
 const COLUMNS: TableColumn<HiveStatus>[] = [
-  { key: "name", header: "name", render: (h) => h.name },
+  {
+    key: "name",
+    header: "name",
+    render: (h) => h.name,
+    sortBy: (h) => h.name,
+    filterValue: (h) => h.name,
+  },
   {
     key: "domain",
     header: "domain",
@@ -61,6 +67,8 @@ const COLUMNS: TableColumn<HiveStatus>[] = [
       ) : (
         "—"
       ),
+    sortBy: (h) => h.domain ?? "",
+    filterValue: (h) => h.domain ?? "",
   },
   {
     key: "status",
@@ -82,6 +90,8 @@ const COLUMNS: TableColumn<HiveStatus>[] = [
         />
       );
     },
+    sortBy: (h) => FRESHNESS[h.freshness].label,
+    filterValue: (h) => FRESHNESS[h.freshness].label,
   },
 ];