Add checkout/custody feature for tracking items in personal possession

Items can now be checked out of their bin into "my custody" and later
checked back in or marked consumed. Adds checkout/checkin API endpoints,
a My Custody sidebar page, CheckoutFlow and CheckinFlow modals, and
updates ProductDetail, Inventory, ConsumeFlow, and MarkGoneFlow to
handle the new checked-out status. Bulk items prompt for remaining
weight on check-in.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/src/routes/inventory.ts

@@ -212,6 +212,67 @@ inventoryRouter.patch("/inventory/:id", (req, res) => {
   res.json({ ok: true });
 });
 
+inventoryRouter.post("/inventory/:id/checkout", (req, res) => {
+  const { id } = req.params;
+  const { date } = req.body as { date: string };
+  const result = db
+    .prepare(
+      `UPDATE inventory_items
+         SET status = 'checked-out', checkout_date = ?, bin_id = NULL
+       WHERE id = ? AND status = 'active'`,
+    )
+    .run(date, id);
+  if (result.changes === 0) return res.status(404).json({ error: "not found or not active" });
+  res.json({ ok: true });
+});
+
+inventoryRouter.post("/inventory/:id/checkin", (req, res) => {
+  const { id } = req.params;
+  const { date, binId, remainingWeight } = req.body as {
+    date: string;
+    binId: string;
+    remainingWeight?: number;
+  };
+
+  const item = db
+    .prepare<
+      [string],
+      { product_id: string; last_audit_weight: number | null; weight: number }
+    >(
+      `SELECT product_id, last_audit_weight, weight
+         FROM inventory_items WHERE id = ? AND status = 'checked-out'`,
+    )
+    .get(id);
+  if (!item) return res.status(404).json({ error: "not found or not checked-out" });
+
+  const product = db
+    .prepare<[string], { kind: string }>(`SELECT kind FROM products WHERE id = ?`)
+    .get(item.product_id);
+  const isBulk = product?.kind === "bulk";
+
+  const tx = db.transaction(() => {
+    db.prepare(
+      `UPDATE inventory_items
+         SET status = 'active', bin_id = ?, checkout_date = NULL
+       WHERE id = ?`,
+    ).run(binId, id);
+
+    if (isBulk && remainingWeight != null && Number.isFinite(remainingWeight)) {
+      const prev = item.last_audit_weight ?? item.weight;
+      db.prepare(
+        `INSERT INTO audits (inventory_id, date, mode, value, prev_value, confirmed_by)
+         VALUES (?, ?, 'weigh', ?, ?, 'checkin')`,
+      ).run(id, date, remainingWeight, prev);
+      db.prepare(`UPDATE inventory_items SET last_audit_weight = ? WHERE id = ?`).run(
+        remainingWeight,
+        id,
+      );
+    }
+  });
+  tx();
+  res.json({ ok: true });
+});
+
 inventoryRouter.post("/inventory/:id/finish", (req, res) => {
   const { id } = req.params;
   const { date, rating, notes } = req.body as {
@@ -222,8 +283,8 @@ inventoryRouter.post("/inventory/:id/finish", (req, res) => {
   const result = db
     .prepare(
       `UPDATE inventory_items
-         SET status = 'consumed', consumed_date = ?, rating = ?, notes = ?, bin_id = NULL
-       WHERE id = ? AND status = 'active'`,
+         SET status = 'consumed', consumed_date = ?, rating = ?, notes = ?, bin_id = NULL, checkout_date = NULL
+       WHERE id = ? AND status IN ('active', 'checked-out')`,
     )
     .run(date, rating ?? null, notes ?? null, id);
   if (result.changes === 0) return res.status(404).json({ error: "not found or not active" });
@@ -242,8 +303,8 @@ inventoryRouter.post("/inventory/:id/gone", (req, res) => {
     const result = db
       .prepare(
         `UPDATE inventory_items
-           SET status = 'gone', gone_date = ?, notes = ?, bin_id = NULL
-         WHERE id = ? AND status = 'active'`,
+           SET status = 'gone', gone_date = ?, notes = ?, bin_id = NULL, checkout_date = NULL
+         WHERE id = ? AND status IN ('active', 'checked-out')`,
       )
       .run(date, combinedNotes, id);
     if (result.changes === 0) throw new Error("not found");