bug: RPCStream initSubscriptions panics on CometBFT subscribe failure, crashing node

[Aboudjem]

Bug Description

In rpc/stream/rpc.go, initSubscriptions() uses panic(err) when CometBFT event subscription fails (lines ~91, ~99). Any transient CometBFT connectivity issue crashes the entire RPC process instead of degrading gracefully.

Impact

• Network blips, slow starts, or reconnection attempts crash the node permanently
• The node must be manually restarted
• Subscription streams are called lazily via HeaderStream()/LogStream(), so the panic can happen at any time

Proposed Fix

Replace panic(err) with s.logger.Error(...) + return. Streams are allocated before subscribe, so callers get non-nil empty streams that degrade gracefully.

[linear]

EVM-442

[swift1337]

Closing for being a low-effort AI submission.