feat(rpc): make pause admin address configurable via CLI flag

[Zhekinmaksim]

Closes #436.

This removes the hardcoded production pause-admin TODO from rpc/src/auth.rs by making the address configurable via --pause-admin-address. The flag defaults to the current constant, so existing permissioned deployments keep the same behavior unless they opt into a different admin address.

The address is now parsed once at startup and the node fails fast on misconfiguration instead of surfacing an error on the first emergency pause/unpause call. The configured admin address is threaded from RunFlags through RPC startup into SummitRpcServer, and the permissioned auth path verifies against that explicit address.

I also updated the permissioned RPC integration tests and the node bin helpers that construct RunFlags manually so the workspace continues to compile under --features permissioned.

Validation:

• cargo fmt --check
• cargo check -p summit-rpc --features permissioned
• cargo test -p summit-rpc --features permissioned
• cargo check -p summit --features permissioned
• cargo clippy --features permissioned

Opened against main, which is the current default branch. If you would prefer this on another active audit branch, I can retarget.

[matthias-wright]

#436 (comment)