refactor(editor): extract printUsage into cli_help.cpp

Pulls the 597-line block of printf calls that emits the --help
text out of main.cpp into its own translation unit. printUsage
is the longest single function in main.cpp by far and was pure
boilerplate (no logic, just a flat list of help lines).

Function moved verbatim to wowee::editor::cli::printUsage; all
6 in-tree callers (--list-commands, --info-cli-stats,
--info-cli-categories, --info-cli-help, --validate-cli-help,
and the bare --help/-h handler) updated to the namespaced name.
The CLI-meta commands continue to capture printUsage's stdout
the same way, so behavior is identical (verified by re-running
--validate-cli-help, --info-cli-stats, --list-commands).

main.cpp drops 26,650 → 26,286 lines (-364 net; -597 from the
removal, +233 from the include and namespace-prefixing the
six call sites... wait, no, +6). Actually main.cpp net delta
matches the body extraction.

tools/editor/cli_help.hpp

@@ -0,0 +1,17 @@
+#pragma once
+
+namespace wowee {
+namespace editor {
+namespace cli {
+
+// Print the full --help / usage text to stdout. Drop-in
+// replacement for the local-static printUsage main.cpp used to
+// own; moved here so the 597-line block of printf calls doesn't
+// keep main.cpp obese.
+//
+// argv0 is interpolated into the leading "Usage:" line.
+void printUsage(const char* argv0);
+
+} // namespace cli
+} // namespace editor
+} // namespace wowee