Initial implementation of inventree

A small IT asset inventory system built around a nested folder tree,
matching the project brief: Go + html/template + Bootstrap 5 + vanilla JS,
SQLite storage (WAL, FKs, migrations), embedded templates/static assets,
single compiled binary.

- AJAX-driven inventory tree: lazy-loaded folder expansion with per-user
  persisted expand state, drag-and-drop move for folders/assets, safe
  delete-with-relocate-or-cascade confirmation, search with breadcrumbs.
- Assets: CRUD, duplicate, move, auto-generated IT-000001-style IDs,
  CSV import (with optional folder auto-create) and export.
- Admin-defined item types with custom fields (text/long_text/number/date/
  boolean/dropdown/url/ip_address).
- Configurable statuses, session-based auth (bcrypt, secure cookies),
  admin/user roles, user management.
- CLI: serve, version, database migrate, database backup; /healthz;
  graceful shutdown; Dockerfile/docker-compose/systemd unit; Go test suite.

web/static/css/app.css

@@ -0,0 +1,184 @@
+:root {
+  --tree-indent: 1.15rem;
+}
+
+body {
+  background-color: #f7f8fa;
+}
+
+.app-navbar {
+  background-color: #fff;
+}
+
+.login-body {
+  min-height: 100vh;
+  background: linear-gradient(180deg, #eef1f6 0%, #f7f8fa 100%);
+}
+
+/* Admin-only UI: shown only when <body> carries the role-admin class. */
+.admin-only { display: none !important; }
+body.role-admin .admin-only { display: inherit !important; }
+body.role-admin button.admin-only,
+body.role-admin a.admin-only { display: inline-block !important; }
+
+.inventory-shell {
+  height: calc(100vh - 56px);
+  min-height: 480px;
+}
+
+.tree-pane {
+  width: 340px;
+  min-width: 260px;
+  max-width: 45vw;
+  background-color: #fff;
+  flex-shrink: 0;
+}
+
+.tree-scroll {
+  overflow-y: auto;
+}
+
+.main-panel {
+  background-color: #fff;
+}
+
+ul.tree, ul.tree-children {
+  list-style: none;
+  margin: 0;
+  padding-left: 0;
+}
+
+ul.tree-children {
+  padding-left: var(--tree-indent);
+}
+
+.tree-node-root > .tree-row {
+  font-weight: 600;
+}
+
+.tree-row {
+  display: flex;
+  align-items: center;
+  gap: 0.35rem;
+  padding: 0.2rem 0.4rem;
+  border-radius: 0.25rem;
+  cursor: pointer;
+  white-space: nowrap;
+  user-select: none;
+}
+
+.tree-row:hover {
+  background-color: #f1f3f5;
+}
+
+.tree-row.selected {
+  background-color: #e7f1ff;
+  color: #0d6efd;
+  font-weight: 500;
+}
+
+.tree-row.drop-target {
+  outline: 2px dashed #0d6efd;
+  outline-offset: -2px;
+  background-color: #e7f1ff;
+}
+
+.tree-row-more {
+  cursor: default;
+}
+
+.tree-toggle {
+  border: none;
+  background: none;
+  padding: 0;
+  width: 1.1rem;
+  height: 1.1rem;
+  display: inline-flex;
+  align-items: center;
+  justify-content: center;
+  flex-shrink: 0;
+  color: #6c757d;
+}
+
+.tree-toggle i {
+  transition: transform 0.12s ease;
+}
+
+.tree-toggle.expanded i {
+  transform: rotate(90deg);
+}
+
+.tree-toggle-spacer {
+  width: 1.1rem;
+  flex-shrink: 0;
+  display: inline-block;
+}
+
+.tree-icon {
+  flex-shrink: 0;
+}
+
+.tree-label {
+  overflow: hidden;
+  text-overflow: ellipsis;
+  flex: 1 1 auto;
+}
+
+.tree-status-badge {
+  font-size: 0.65rem;
+  flex-shrink: 0;
+}
+
+.tree-actions {
+  flex-shrink: 0;
+}
+
+.btn-tree-action {
+  border: none;
+  background: none;
+  color: #6c757d;
+  padding: 0 0.25rem;
+}
+
+.btn-tree-action:hover {
+  color: #212529;
+}
+
+.tree-node.dragging {
+  opacity: 0.4;
+}
+
+.stat-card .card-body {
+  text-align: center;
+}
+
+.stat-value {
+  font-size: 1.4rem;
+  font-weight: 600;
+  line-height: 1.2;
+}
+
+.stat-label {
+  font-size: 0.75rem;
+  color: #6c757d;
+}
+
+.panel-content {
+  max-width: 1100px;
+}
+
+.asset-row, .folder-link, .asset-link {
+  cursor: pointer;
+}
+
+@media (max-width: 767.98px) {
+  .inventory-shell {
+    flex-direction: column;
+    height: auto;
+  }
+  .tree-pane {
+    width: 100%;
+    max-width: 100%;
+    max-height: 40vh;
+  }
+}