feat: purge legacy agent hosts and land vault Chrome extension path

Retire ACP/Hermes/OpenCode surfaces and rename hermes_tools to
mnote_agent_tools so Page AI stays on Pi Lab only. Add Chrome vault
extension + extension token route, pre-release purge design, and soft-retire
legacy smokes for the small-group production cut.

rust/crates/mnote-web/src/ssr/styles/components/vault.css

@@ -456,6 +456,44 @@
   border-top: 1px solid rgba(27, 28, 28, 0.06);
 }
 
+/* 账号下登录态（扩展 Cookie session）状态徽章 */
+.mnote-vault-session-badge {
+  display: inline-flex;
+  align-items: center;
+  gap: 4px;
+  padding: 1px 8px;
+  border-radius: 999px;
+  font-size: 11px;
+  font-weight: 600;
+  line-height: 18px;
+  letter-spacing: 0.01em;
+}
+.mnote-vault-session-badge.is-saved {
+  background: rgba(34, 160, 107, 0.12);
+  color: #1a7a4c;
+  border: 1px solid rgba(34, 160, 107, 0.28);
+}
+.mnote-vault-session-badge.is-absent {
+  background: rgba(109, 106, 101, 0.08);
+  color: #6d6a65;
+  border: 1px solid rgba(109, 106, 101, 0.18);
+}
+.mnote-vault-session-badge.is-compact {
+  font-size: 10px;
+  padding: 0 6px;
+  line-height: 16px;
+  margin-left: 6px;
+}
+.mnote-vault-session-meta {
+  display: flex;
+  flex-wrap: wrap;
+  align-items: center;
+  gap: 6px;
+}
+.mnote-vault-session-row > label {
+  min-width: 0;
+}
+
 .mnote-vault-field-row > label {
   padding-top: 4px;
   color: #6d6a65;
@@ -556,6 +594,114 @@
   line-height: 18px;
 }
 
+/* Expand-style folder picker: top-level groups stay visible (no long select). */
+.mnote-vault-folder-picker {
+  width: 100%;
+  box-sizing: border-box;
+  max-height: 220px;
+  overflow: auto;
+  padding: 6px;
+  border: 1px solid rgba(27, 28, 28, 0.12);
+  border-radius: 6px;
+  background: #fafaf9;
+}
+
+.mnote-vault-folder-picker-none {
+  display: block;
+  width: 100%;
+  margin: 0 0 4px;
+  padding: 5px 8px;
+  border: none;
+  border-radius: 4px;
+  background: transparent;
+  color: #6d6a65;
+  font: inherit;
+  font-size: 12px;
+  text-align: left;
+  cursor: pointer;
+}
+
+.mnote-vault-folder-picker-none:hover,
+.mnote-vault-folder-picker-label:hover {
+  background: rgba(35, 131, 226, 0.08);
+  color: #37352f;
+}
+
+.mnote-vault-folder-picker-none.is-selected,
+.mnote-vault-folder-picker-row.is-selected .mnote-vault-folder-picker-label {
+  background: rgba(35, 131, 226, 0.14);
+  color: #1b64c2;
+  font-weight: 600;
+}
+
+.mnote-vault-folder-picker-node {
+  min-width: 0;
+}
+
+.mnote-vault-folder-picker-row {
+  display: flex;
+  align-items: center;
+  gap: 2px;
+  min-height: 26px;
+  padding-left: calc(var(--vault-picker-depth, 0) * 12px);
+  border-radius: 4px;
+}
+
+.mnote-vault-folder-picker-chevron {
+  flex: 0 0 18px;
+  width: 18px;
+  height: 22px;
+  margin: 0;
+  padding: 0;
+  border: none;
+  background: transparent;
+  color: #9b9a97;
+  font: inherit;
+  font-size: 9px;
+  line-height: 22px;
+  text-align: center;
+  cursor: pointer;
+}
+
+.mnote-vault-folder-picker-chevron.is-leaf {
+  cursor: default;
+  visibility: hidden;
+}
+
+.mnote-vault-folder-picker-label {
+  flex: 1 1 auto;
+  min-width: 0;
+  margin: 0;
+  padding: 4px 6px;
+  border: none;
+  border-radius: 4px;
+  background: transparent;
+  color: #37352f;
+  font: inherit;
+  font-size: 13px;
+  line-height: 18px;
+  text-align: left;
+  cursor: pointer;
+  overflow: hidden;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+}
+
+.mnote-vault-folder-picker-children {
+  min-width: 0;
+}
+
+.mnote-vault-folder-picker-empty {
+  padding: 6px 8px;
+  font-size: 12px;
+}
+
+.mnote-vault-folder-hint {
+  margin: 0;
+  font-size: 11px;
+  color: #9b9a97;
+}
+
 .mnote-vault-folder-controls input[type="text"] {
   width: 100%;
   box-sizing: border-box;