feat(03-04): Task 1 — driveA32 host-side Page.metrics scaffolding + orchestrator wiring

A32 ships ~90 lines of best-effort RAM scaffolding per D-P3-04 +
RESEARCH Open Question 3 (recommended SHIP). Calls puppeteer.Page.metrics()
against the harness page and asserts JSHeapUsedSize is below the SPEC §10 #9
50 MB ceiling.

Page-realm scope is the load-bearing caveat (RESEARCH Pitfall 2): the MV3
service worker is a separate Puppeteer target with its own V8 isolate, so
Page.metrics() under-reports the operator-facing "extension background
RAM" measurement that §10 #9 actually requires. The binding §10 #9 gate
stays operator-driven (chrome://memory-internals OR chrome://extensions
service-worker memory display) and is recorded in Plan 03-05 VERIFICATION.md
human_verification block.

Mandatory diagnostic line emitted on EVERY run regardless of pass/fail:
"NOTE: page-realm only; SW context measurement requires
chrome://memory-internals operator verification per D-P3-04."
printAssertionResult prints diagnostics to stdout so the operator sees
the caveat in the live UAT trace, never confusing automation GREEN with
full §10 #9 closure (T-03-04-01 Repudiation mitigation).

Host-side only — no page-side assertA32, no setupFreshRecording, no
SAVE, no archive parse. driveA32 takes only `page` (no downloadsDir),
so the orchestrator pushes it bare in the drivers array without a wrapped
const. Tier-1 FORBIDDEN_HOOK_STRINGS inventory unchanged at 12 entries
(Page.metrics is host-side puppeteer; not bundled).

Empirical: UAT harness 32/32 → 33/33 GREEN; A32.1 PASS (JSHeapUsedSize=
1909924 bytes); A32.2 PASS (1.82 MB << 50 MB). Tier-1 unit-gate 13/13
sub-tests GREEN; 12 strings × 0 hits each in dist/. vitest 171/171 GREEN.

Closes:
- Plan 03-04 must_have 'puppeteer.Page.metrics() returns a JSHeapUsedSize
  value (>= 0) for the harness page realm' (A32.1)
- Plan 03-04 must_have 'JSHeapUsedSize for the harness page realm is
  below 50 MB' (A32.2)
- Plan 03-04 must_have 'Driver emits an explicit diagnostic line: NOTE:
  page-realm only' (Pitfall 2 gate — leads diagnostics array)
- Plan 03-04 must_have 'UAT harness exits 0 with 32 + 1 = 33/33
  assertions GREEN' (empirical 33/33)

tests/uat/harness.test.ts

@@ -103,6 +103,8 @@ import {
   driveA30,
   // Plan 03-03 — password-filter PARTIAL (SPEC §10 #8 PARTIAL per D-P3-02)
   driveA31,
+  // Plan 03-04 — RAM scaffolding best-effort (SPEC §10 #9 per D-P3-04)
+  driveA32,
   getManifestVersion,
 } from './lib/harness-page-driver';
 import {
@@ -271,7 +273,7 @@ async function assertA0_GrepGate(): Promise<{
  */
 async function main(): Promise<number> {
   process.stdout.write('\nMokosh Plan 01-13 + 01-14 + 02-04 — UAT harness orchestrator\n');
-  process.stdout.write('Architecture: A0 pre-flight + extension-internal page driver (A1..A14, A15..A17, A18..A22, A23, A24, A25, A26, A27, A28, A29, A30, A31)\n');
+  process.stdout.write('Architecture: A0 pre-flight + extension-internal page driver (A1..A14, A15..A17, A18..A22, A23, A24, A25, A26, A27, A28, A29, A30, A31, A32)\n');
   process.stdout.write('='.repeat(72) + '\n');
 
   // A0 pre-flight (no Chrome launch needed; runs against built dist/).
@@ -475,6 +477,13 @@ async function main(): Promise<number> {
     // mean the filter actually fired rather than the trivial "no
     // events at all" tautology).
     { name: 'A31', drive: driveA31Wrapped },
+    // Plan 03-04 A32: RAM scaffolding (SPEC §10 #9 best-effort per D-P3-04).
+    // NOTE — Page.metrics is page-realm only; SW context is a separate
+    // Puppeteer target (RESEARCH Pitfall 2). A32 is informational
+    // scaffolding; the binding §10 #9 gate lives in Plan 03-05
+    // VERIFICATION.md `human_verification` block. No wrapped const
+    // needed — driveA32 takes only `page`.
+    { name: 'A32', drive: driveA32 },
   ];
 
   const buffers = { swConsole: handles.swConsole, offConsole: handles.offConsole };