Plan the idiomatic-Go refactor in TODO.md

Itemize the refactor from transliterated port to idiomatic Go: eight
stepped feature branches (descriptive constant renames, typed kind
enums, un-overloaded Object fields, per-subsystem method renames,
god-object extraction, effects dispatch tables, constructor/style
pass, docs refresh), slotted ahead of the existing playtest/lint/
release steps. Also add the styleguide-required .gitignore (a stray
built binary was sitting untracked in the root).

.gitignore

@@ -0,0 +1,4 @@
+*.log
+*.out
+*.test
+/rogue