Remove dead ipc code

[RickiNano]

Removes IPC code that was never reachable:

• ipc_server::signals - a shared_ptr<signal_set> that was never assigned, making the signals->cancel() branch in stop() permanently dead. Drops the member, the branch, and the now-unused <boost/asio/signal_set.hpp> include.
• ipc_server::setup_callbacks() - declared but never defined or called.
• The ipc_server instance in the --debug_rpc CLI path - constructed and never used. json_handler doesn't take an ipc_server.
• The ipc_server.hpp include in nano_rpc/entry.cpp, which only needs ipc_rpc_processor.

No functional change.

[gr0vity-dev-bot]

Test Results for Commit 4388f96

Pull Request 5157: Results
Overall Status: ❌

Test Case Results

• ✅ 5n4pr_conf_10k_bintree: PASS (Duration: 122s)
• ✅ 5n4pr_conf_10k_change: PASS (Duration: 123s)
• ❌ 5n4pr_conf_change_dependant: FAIL (Duration: 3s)
• Log
• ✅ 5n4pr_conf_change_independant: PASS (Duration: 108s)
• ✅ 5n4pr_conf_send_dependant: PASS (Duration: 108s)
• ✅ 5n4pr_conf_send_independant: PASS (Duration: 111s)
• ✅ 5n4pr_rocks_10k_bintree: PASS (Duration: 115s)
• ✅ 5n4pr_rocks_10k_change: PASS (Duration: 160s)

Last updated: 2026-08-30 19:56:35 UTC