refactor(#1005): rename capabilities → tool-groups throughout UI

Section heading, element id, CSS classes, and JS functions all renamed
from 'capabilities'/'cap-*' to 'tool-groups'/'tg-*' to accurately
describe what the UI manages (tool-group permissions, not a capabilities
system).

frontend/packages/dashboard/src/dashboard.css

@@ -2045,55 +2045,55 @@ body.logs-shell {
   font-size: 0.85em;
 }
 
-/* ─── capabilities (tool-group) table ──────────────────────────────
+/* ─── tool-groups (permissions) table ──────────────────────────────
    Agents × tool-groups matrix in the SYST3M tab. Horizontally
    scrollable on narrow viewports. */
-.cap-table-wrap {
+.tg-table-wrap {
   overflow-x: auto;
   margin-top: 0.5em;
 }
-.cap-table {
+.tg-table {
   border-collapse: collapse;
   font-size: 0.82em;
   min-width: 100%;
 }
-.cap-table th,
-.cap-table td {
+.tg-table th,
+.tg-table td {
   padding: 0.35em 0.6em;
   border: 1px solid var(--border);
   text-align: center;
   vertical-align: middle;
 }
-.cap-table thead th {
+.tg-table thead th {
   background: var(--bg-elev);
   color: var(--muted);
   letter-spacing: 0.05em;
   white-space: nowrap;
 }
-.cap-agent-col {
+.tg-agent-col {
   text-align: left !important;
   min-width: 8em;
 }
-.cap-agent-name {
+.tg-agent-name {
   color: var(--fg);
   font-weight: 600;
 }
-.cap-default-label {
+.tg-default-label {
   margin-left: 0.4em;
   font-size: 0.85em;
 }
-.cap-cb {
+.tg-cb {
   cursor: pointer;
   width: 1em;
   height: 1em;
   accent-color: var(--purple);
 }
-.cap-save-btn {
+.tg-save-btn {
   font-size: 0.78em;
   padding: 0.2em 0.6em;
   white-space: nowrap;
 }
-.cap-row:hover td {
+.tg-row:hover td {
   background: var(--bg-elev);
 }