[chiliec]

Second pass after #213: find code that is compiled but never linked, using the linker itself rather than grep.

Method. Relink all 23 executables (vizd, cli_wallet, 14 ctest binaries, util tools, appbase_example, chainbase_test) with -Wl,-map, collect which static-archive members each one loads, diff against ar t. A member no binary loads, whose header no live file includes, is dead. Cross-checked with an nm symbol-reference graph.

Removed here

• libraries/api: discussion_helper.{hpp,cpp}, content_api_object.{hpp,cpp}, discussion.hpp, vote_state.hpp, account_vote.hpp — Steem discussion-API leftovers, included only by each other.
• libraries/chain/chain_objects.cpp — 121 lines, all commented out.
• libraries/utilities: string_escape, tempdir, padding_ostream.hpp — no includer.
• wallet.hpp: stale <fc/real128.hpp> include. wallet/CMakeLists.txt: an add_custom_command whose output no target consumed.
• Workflows: the five sed -i '/add_subdirectory(tests)/d' thirdparty/fc/CMakeLists.txt lines, now that fc defaults BUILD_FC_TESTS to OFF.

Removed in fc (VIZ-Blockchain/fc#5, submodule bumped): 17 modules + the cyoencode vendor lib + src/ssh/pke that were never built. Table and rationale in that PR. Merge fc#5 first.

Honest numbers

	CPU-s	share of full build (~43 CPU-min)
dead fc TUs (23)	32	1.2 %
dead VIZ TUs (5)	34	1.3 %
appbase_example + chainbase_test (left alone, only built by make all, not by Docker/CI)	13	0.5 %

This is cleanup, not a speedup. Everything else in the tree is loaded by some binary. The build time lives in the top five TUs (database.cpp 248 s, wallet.cpp 162 s, dlt_p2p_node.cpp 130 s, operations.cpp 127 s, snapshot/plugin.cpp 102 s) and is optimizer time on fc::raw visitor instantiations, as profiled in #213. Cutting that means explicit instantiation of the block/operation serializers or splitting database.cpp, which is a different PR.

Verification

• Full native build on Apple Silicon: vizd, cli_wallet, all 14 test binaries, util tools link. 13/13 fast ctest pass. consensus_sim runs in CI.
• Labels check-arm64 + check-boost-range added so the distro-Boost 1.83 and arm64 jobs exercise the fc CMake change.