fix(extension): emit no modulepreload links, which Chrome refuses to use

[stormer78]

Every generated wallet page carried a <link rel="modulepreload" crossorigin> for each shared chunk its entry imports, and Chrome declined all of them:

A preload for 'chrome-extension://…/assets/bridge-protocol-….js' is found, but is not used because it is a cross-world extension resource mismatch.

The hint is fetched under a different resource world than the module graph that <script type="module"> then loads, so the preloaded copy never matches the lookup and is discarded — each chunk fetched twice, and 18 warnings across popup (4), options (6), confirm (4) and offscreen (4) on the chrome://extensions Errors page.

Nothing was broken by them; the script tag is what actually loads the graph. The cost is the page they filled. The Errors page is where a real fault has to be noticed, and a screenful of benign warnings is how one gets scrolled past — the same reasoning R7.2 applies to a lost prompt.

Preloading buys nothing here anyway: every asset is read from local disk, with no network latency to hide. manager.html never had any, because codeSplitting: false leaves the console no shared chunks to preload, and background.js is a single bundle with no HTML at all — so vite.config.ts is the one config that needed the option.

Verification

Built both ways and counted the links:

page	before	after
popup.html	4	0
options.html	6	0
confirm.html	4	0
offscreen.html	4	0

The entry's own <script type="module" crossorigin src="…"> is unchanged, which is the tag that actually loads.

• npm run build --workspace @openvtc/pnm-extension (all three configs) — clean
• npm test --workspace @openvtc/pnm-extension — 726 pass, 0 fail
• dist guards re-run locally: background.js has no dynamic import(); acl/*, contexts/delete, keys/sign and persona/attribute/put appear in no file but manager.js; no vta/seeds/* anywhere; no manager-split-*.js; packaged manifest has no content_scripts; no chrome.cookies in dist/

Pre-merge checklist (vti-stack-development-guide.md)

• No cross-service wire contract touched — this is a bundler output option only
• No compatibility fold added
• No new fetch, endpoint or error-matching path (R1.2 / R3.7 unaffected)
• MV3 invariants intact: single background.js bundle, codeSplitting: false on the console build