Connect a wallet and gate the app on network and allowlist

[luchobonatti]

User story / Problem statement

The app has to know who is connected, on which network, and whether that address may subscribe.

Expected outcome

Connection, network and allowlist come from the chain instead of mock state.

Acceptance criteria

• Not-connected and wrong-network screens are driven by real wallet state
• Allowlist status is read from the identity verifier
• A non-allowlisted investor sees that screen, not an error
• Metrics read as unavailable on the wrong network
• Nothing is stored in a session or a backend

Technical notes

The contract exposing the allowlist today is a stub, and its shape changes when the compliance module lands. Blocked by #84. Parent: #30.