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/templates/login.html

@@ -0,0 +1,43 @@
+{{define "login"}}<!doctype html>
+<html lang="en" data-bs-theme="light">
+<head>
+  <meta charset="utf-8">
+  <meta name="viewport" content="width=device-width, initial-scale=1">
+  <title>Sign in · inventree</title>
+  <link rel="stylesheet" href="/static/css/bootstrap.min.css">
+  <link rel="stylesheet" href="/static/icons/bootstrap-icons.css">
+  <link rel="stylesheet" href="/static/css/app.css">
+</head>
+<body class="login-body d-flex align-items-center">
+  <div class="container">
+    <div class="row justify-content-center">
+      <div class="col-11 col-sm-8 col-md-5 col-lg-4">
+        <div class="text-center mb-4">
+          <div class="display-6"><i class="bi bi-diagram-3-fill"></i></div>
+          <h1 class="h4 mt-2 mb-0">inventree</h1>
+          <div class="text-body-secondary small">IT asset inventory</div>
+        </div>
+        <div class="card shadow-sm">
+          <div class="card-body p-4">
+            {{if .Error}}<div class="alert alert-danger py-2">{{.Error}}</div>{{end}}
+            <form method="post" action="/login">
+              <input type="hidden" name="next" value="{{.Next}}">
+              <div class="mb-3">
+                <label class="form-label" for="username">Username</label>
+                <input class="form-control" type="text" id="username" name="username" autofocus required autocomplete="username">
+              </div>
+              <div class="mb-3">
+                <label class="form-label" for="password">Password</label>
+                <input class="form-control" type="password" id="password" name="password" required autocomplete="current-password">
+              </div>
+              <button type="submit" class="btn btn-primary w-100">Sign in</button>
+            </form>
+          </div>
+        </div>
+        <p class="text-center text-body-secondary small mt-3">Default login: admin / admin</p>
+      </div>
+    </div>
+  </div>
+</body>
+</html>
+{{end}}