test(rest): give the import-template parity case a measured per-shape budget

The parity case in import-template-route.test.ts loops over 20 default
shapes. The loop is 98% of the case under every load measured, and the
engine boot is warm by the time the case runs. So the case gets an
explicit timeout of 1000ms per shape (20000ms for 20 shapes), with the
measured timings and the arithmetic in a comment above it. No assertion
changes.

Claude-Session: https://claude.ai/code/session_016GiHYRmLSNWTfbX9gVQkpz
Co-Authored-By: Claude <noreply@anthropic.com>

Author: claude

packages/rest/src/import-template-route.test.ts

@@ -507,6 +507,36 @@ const PARITY: Record<string, { def: Record<string, unknown>; blank: 'refused' |
   },
 };
 
+/**
+ * The parity case's own budget (#21428): {@link PARITY_MS_PER_SHAPE} per shape,
+ * so it grows with the battery. Vitest's default 5000ms is one budget for the
+ * whole case, and this case is a loop. It ran past 5000ms twice on a loaded
+ * Test Core shard.
+ *
+ * Measured with phase timers in a throwaway copy of this file, on a 4-vCPU box
+ * that other jobs shared. The whole file ran each time, so this case ran after
+ * the 25 cases above it, as it does in CI.
+ *
+ *   load                         whole case    boot     register+sync  loop
+ *   idle, 5 runs                 941-1085ms    5-6ms    14-15ms        920-1063ms
+ *   2 runs of the file at once   1105-1671ms   5-7ms    15-21ms        1084-1642ms
+ *   8 busy loops, 3 runs         2232-2632ms   9-10ms   31-46ms        2190-2576ms
+ *   24 busy loops, 3 runs        7654-8371ms   36-44ms  91-142ms       7525-8165ms
+ *
+ * The loop is 98% of the case under every load, and its cost is the work this
+ * case asserts on. Each shape builds a template through the real route, parses
+ * the workbook, and imports a row through the real import door, about a third
+ * of the loop each. The engine boot is already warm at this point in the file,
+ * and boot plus registering and syncing the 20 objects is 2% of the case, so
+ * moving the boot into a `beforeAll` would not fix this.
+ *
+ * The budget per shape: the slowest per-shape cost measured above is 419ms
+ * (8371ms / 20, at 24 busy loops). 1000ms is about 2.4x that, and about 18x the
+ * slowest idle cost (1085ms / 20 = 54ms). For the 20 shapes here the case gets
+ * 20000ms.
+ */
+const PARITY_MS_PER_SHAPE = 1_000;
+
 describe('the `*` agrees with the engine: starred exactly when the import door refuses a blank', () => {
   it('for every shape of default the engine reads', async () => {
     const { get, importRoute, engine } = await boot();
@@ -546,7 +576,7 @@ describe('the `*` agrees with the engine: starred exactly when the import door r
       }
     }
     expect(disagreements).toEqual([]);
-  });
+  }, Object.keys(PARITY).length * PARITY_MS_PER_SHAPE);
 });
 
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