fix: add iroh:// protocol support

[BHARATH0153]

Adds Iroh as a new transport protocol, following step 1-3 of the issue checklist:

URL scheme: iroh://<node-id>/<path> where <node-id> is the base32-encoded public key of the target node.

What this PR does:

• Registers the iroh:// privileged scheme in Electron
• Creates handler (src/protocols/iroh-protocol.js) that connects to an iroh node via @number0/iroh, opens a bidirectional QUIC stream, sends an HTTP-like request, and returns the response
• Adds @number0/iroh v0.35.0 as a dependency
• Adds config irohOptions.storage (defaults to same dir as hyper)
• Registers protocol in build config for OS-level protocol handling

Not yet done (next PRs):

• Proper HTTP/3 framing via iroh-h3 (currently uses simple request/response over bi-stream)
• DNSSEC/DNSLink resolution for iroh node IDs
• iroh server side (serve agregore website)
• Relay server on Agregore infrastructure
• LLM endpoint resolution over iroh

Closes #336