feat: add Who I Am as pre-approved trust certifier

[sirdeggen]

Summary

• Adds Who I Am (https://whoiam.bsvblockchain.tech) to the app-level default trust certifiers list, matching the approach already used in bsv-browser.
• Extends library DEFAULT_SETTINGS with the certifier (identity key, icon, trust score 5) and applies it via settingsManager.config before the first settings load so new wallets get it automatically.

Details

Pre-approved entry:

Field	Value
Name	Who I Am
Description	Certifies email, phone, and X account ownership
Icon	https://whoiam.bsvblockchain.tech/whoiam.png
Identity key	02e7eeb3986273db6843b790a1595ed0ff1b2ae8f43ae2e7f1a0c9db4dd3fb9441
Trust	5

Test plan

• Fresh wallet setup: open Trust Network page and confirm Who I Am appears in the default certifiers list
• Confirm Metanet Trust Services and SocialCert still appear as before
• Existing wallet with saved settings: verify settings are unchanged (defaults only apply when no settings token exists yet)
• Optional: verify Who I Am icon loads from https://whoiam.bsvblockchain.tech/whoiam.png