feat(common): read the memory text the client sends at login

The login request's memoryStats is a run of short parts with no separators
(process working set and private bytes, memory load, physical memory, commit
limit, the 32-bit client's own address space, peaks). ParseMemoryStats splits
it into numbers; a text cut short keeps the parts before the cut.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

dCommon/ClientSysInfo.cpp

@@ -0,0 +1,61 @@
+#include "ClientSysInfo.h"
+
+#include <array>
+#include <cctype>
+#include <charconv>
+
+namespace {
+	struct Reader {
+		std::string_view text;
+		size_t pos{};
+
+		void SkipSpace() {
+			while (pos < text.size() && std::isspace(static_cast<unsigned char>(text[pos]))) pos++;
+		}
+
+		bool Literal(std::string_view literal) {
+			SkipSpace();
+			if (text.substr(pos, literal.size()) != literal) return false;
+			pos += literal.size();
+			return true;
+		}
+
+		std::optional<int64_t> Number() {
+			SkipSpace();
+			int64_t value{};
+			const auto* begin = text.data() + pos;
+			const auto [end, error] = std::from_chars(begin, text.data() + text.size(), value);
+			if (error != std::errc{} || end == begin) return std::nullopt;
+			pos += static_cast<size_t>(end - begin);
+			return value;
+		}
+	};
+}
+
+ClientSysInfo::MemoryStats ClientSysInfo::ParseMemoryStats(const std::string_view text) {
+	MemoryStats stats;
+	// Each part: text before the number, text after it, and where the number goes
+	struct Part { std::string_view prefix; std::string_view suffix; std::optional<int64_t> MemoryStats::* field; };
+	const std::array<Part, 11> parts{ {
+		{ "", "p,", &MemoryStats::workingSetBytes },
+		{ "", "vbytes.", &MemoryStats::pagefileUsageBytes },
+		{ "", "n-use.", &MemoryStats::memoryLoadPercent },
+		{ "", "TKb-pmem.", &MemoryStats::totalPhysKb },
+		{ "", "FKb pmem.", &MemoryStats::availPhysKb },
+		{ "", "TKb pfile.", &MemoryStats::totalPageFileKb },
+		{ "", "FKb pfile.", &MemoryStats::availPageFileKb },
+		{ "", "TKbytes vmem.", &MemoryStats::totalVirtualKb },
+		{ "", "FKb vmem.", &MemoryStats::availVirtualKb },
+		{ "P", "p,", &MemoryStats::peakWorkingSetBytes },
+		{ "", "v.", &MemoryStats::peakPagefileUsageBytes },
+	} };
+	Reader reader{ text };
+	for (const auto& part : parts) {
+		if (!part.prefix.empty() && !reader.Literal(part.prefix)) return stats;
+		const auto value = reader.Number();
+		if (!value || !reader.Literal(part.suffix)) return stats;
+		stats.*part.field = *value;
+	}
+	stats.complete = true;
+	return stats;
+}