fix(widget): support did:keri DIDs and P-256 did:key in auto-resolver

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Description

The TS auto-resolver in packages/widget/src/resolvers/github.ts and packages/widget/src/resolvers/did-utils.ts cannot resolve standard identities generated by the auths CLI.

Root Cause

1. In packages/widget/src/resolvers/github.ts (lines 91-98):

if (controllerDid.startsWith('did:key:z')) {
  publicKeyHex = didKeyToPublicKeyHex(controllerDid);
} else {
  return {
    bundle: null,
    error: `Cannot extract public key from ${controllerDid}. Only did:key is supported for auto-resolve.`,
  };
}

auths init creates did:keri:... identities by default, but github.ts explicitly rejects did:keri.

2. In packages/widget/src/resolvers/did-utils.ts (lines 57-62):

if (decoded.length < 34 || decoded[0] !== 0xed || decoded[1] !== 0x01) {
  throw new Error(`Expected Ed25519 multicodec prefix (0xED 0x01)...`);
}

didKeyToPublicKeyHex hardcodes checking for the Ed25519 multicodec prefix 0xed 0x01. However, auths init defaults to P-256 keys (multicodec 0x1200), causing didKeyToPublicKeyHex to throw an unhandled Error.

Expected Behavior

• The resolver should support resolving did:keri DIDs by parsing inception events or KEL state.
• didKeyToPublicKeyHex should support P-256 did:key multicodec prefix (0x1200) in addition to Ed25519 (0xed 0x01).

Location

• packages/widget/src/resolvers/github.ts
• packages/widget/src/resolvers/did-utils.ts

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Companion issue created in auths-dev/auths: auths-dev/auths#407 to expose the WASM helper resolveKeriActiveKey for dynamic KERI state resolution.