feat(core): add bounded people picker foundation

webui/src/styles/components.css

@@ -1516,6 +1516,166 @@
   display: none;
 }
 
+/* Principal-aware account/contact picker with structured external entry. */
+.people-picker {
+  display: grid;
+  gap: 16px;
+  min-width: 0;
+}
+.people-picker-search-field,
+.people-picker-selection,
+.people-picker-manual {
+  display: grid;
+  gap: 7px;
+  min-width: 0;
+}
+.people-picker-search-control {
+  position: relative;
+  display: flex;
+  align-items: center;
+}
+.people-picker-search-control > svg {
+  position: absolute;
+  left: 12px;
+  z-index: 1;
+  color: var(--muted);
+  pointer-events: none;
+}
+.people-picker-search-control input {
+  padding-left: 38px;
+}
+.people-picker-search-control:focus-within > svg {
+  color: var(--primary);
+}
+.people-picker-results {
+  display: grid;
+  max-height: 360px;
+  overflow: auto;
+  border: var(--border-line-dark);
+  border-radius: 8px;
+  background: var(--surface);
+  box-shadow: var(--shadow-popover);
+  padding: 5px;
+}
+.people-picker-result-group {
+  display: grid;
+  gap: 2px;
+}
+.people-picker-result-group + .people-picker-result-group {
+  margin-top: 5px;
+  border-top: var(--border-line);
+  padding-top: 5px;
+}
+.people-picker-result-group-label {
+  color: var(--text-label);
+  font-size: 11px;
+  font-weight: 800;
+  letter-spacing: .04em;
+  padding: 5px 9px 3px;
+  text-transform: uppercase;
+}
+.people-picker-result {
+  display: grid;
+  grid-template-columns: minmax(0, 1fr) minmax(120px, auto);
+  align-items: center;
+  gap: 16px;
+  width: 100%;
+  border: 0;
+  border-radius: 6px;
+  background: transparent;
+  color: var(--text);
+  cursor: pointer;
+  padding: 8px 9px;
+  text-align: left;
+}
+.people-picker-result:hover:not(:disabled),
+.people-picker-result.is-active:not(:disabled),
+.people-picker-result:focus-visible:not(:disabled) {
+  background: var(--primary-soft);
+  box-shadow: var(--primary-inset-ring);
+  outline: none;
+}
+.people-picker-result:disabled {
+  background: var(--control-disabled-bg);
+  color: var(--control-disabled-text);
+  cursor: not-allowed;
+}
+.people-picker-result-main,
+.people-picker-result-context,
+.people-picker-selected-person {
+  display: grid;
+  gap: 2px;
+  min-width: 0;
+}
+.people-picker-result-main strong,
+.people-picker-result-main small,
+.people-picker-result-context small,
+.people-picker-selected-person strong,
+.people-picker-selected-person small {
+  overflow-wrap: anywhere;
+}
+.people-picker-result-main small,
+.people-picker-result-context,
+.people-picker-selected-person small {
+  color: var(--muted);
+  font-size: 12px;
+}
+.people-picker-result-context {
+  justify-items: end;
+  text-align: right;
+}
+.people-picker-status {
+  min-height: 18px;
+  color: var(--muted);
+  font-size: 12px;
+}
+.people-picker-manual {
+  justify-items: start;
+}
+.people-picker-manual-form {
+  display: grid;
+  grid-template-columns: minmax(160px, 1fr) minmax(220px, 1fr) auto;
+  align-items: end;
+  gap: 12px;
+  width: 100%;
+  border: var(--border-line);
+  border-radius: 8px;
+  background: var(--surface-subtle);
+  padding: 12px;
+}
+.people-picker-manual-form > label {
+  display: grid;
+  gap: 6px;
+  min-width: 0;
+}
+.people-picker-manual-actions {
+  display: flex;
+  align-items: center;
+  gap: 8px;
+}
+.people-picker-manual-form > .form-help {
+  grid-column: 1 / -1;
+  margin: 0;
+}
+.people-picker-selection > .field-label,
+.people-picker-selection > span > .field-label {
+  width: fit-content;
+}
+
+@media (max-width: 760px) {
+  .people-picker-result {
+    grid-template-columns: 1fr;
+    gap: 4px;
+  }
+  .people-picker-result-context {
+    justify-items: start;
+    text-align: left;
+  }
+  .people-picker-manual-form {
+    grid-template-columns: 1fr;
+  }
+}
+
 /* Bootstrap-like switch controls without importing Bootstrap. */
 .toggle-switch-row {
   display: flex;