chore(pg-manual): bump @e4a/pg-wasm to 0.6.0

[dobby-coder]

Closes #35

Bumps @e4a/pg-wasm 0.5.10 → 0.6.0 in pg-manual.

• Public API surface (seal, sealStream, Unsealer, StreamUnsealer) is unchanged between 0.5.10 and 0.6.0; example code needed no edits.
• npm install && npm run build is clean — no "export … was not found" warnings.
• No CI workflow in this repo; reviewer please verify the browser encrypt/decrypt round-trip manually via npm run dev (Yivi/IRMA flow can't run unattended).

Reviewer quickstart: cd pg-manual && npm install && npm run dev

[dobby-coder]

Verification (review-cycle pass; cannot self-approve):

• npm install && npm run build in pg-manual/ is clean — zero "export … was not found" warnings.
• seal, sealStream, Unsealer, StreamUnsealer are all present in @e4a/pg-wasm@0.6.0's bundler/index.d.ts, matching what examples/string.js and examples/file.js import. No example-code edits needed.
• Yivi/IRMA browser round-trip not exercised (interactive).

Looks good to merge from this agent's side.