fix: add explicit STL headers and tighten two non-portable usages

[iamcheyan]

GCC pulls a few common STL headers in transitively, and accepts a
couple of small non-portable patterns that Clang rejects. Apple
Clang and Clang in general do neither, so the project doesn't
compile out of the box on macOS / on a recent libc++ toolchain.

This PR is the minimal fix. None of these changes affect behaviour
or change Linux GCC builds.

Header completeness (transitive on GCC, not on Clang)

• common/src/triangle.cpp — <algorithm> (std::max / std::min)
• common/src/log.hpp — <unistd.h> (getpid())
• common/src/buffrecord.hpp — <cmath> (std::lround)
• common/src/staticvector.hpp — <span> (std::span)
• common/src/protocoldef.hpp — <utility> (std::move / std::forward)
• client/src/layoutboard.cpp — <ranges> (std::views)

Standards-conformance fixes

• common/src/sdruntimeconfig.hpp — replace a =delete-on-template-
  specialization (a GCC extension) with static_assert. Clang
  requires =delete to appear on the first declaration of an
  entity; the existing form was non-standard.
• common/src/zcompf.hpp — pass src directly instead of
  src.data(); the parameter is already a raw const uint8_t *,
  so .data() doesn't compile.

Tested

• Apple Clang 17 (Xcode 17) on macOS arm64 — builds clean.
• brew LLVM 22 on macOS arm64 — builds clean.
• Should be a strict no-op on Linux GCC builds (only adds includes
  and replaces non-portable patterns with portable equivalents).