docs: progression CONTEXT, ADRs 0001-0004, phase A plan

ignore .idea/ .superpowers/ bin/ obj/; drop 3 identical csproj backups

docs/adr/0001-three-progression-scopes.md

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+# Player progression has three scopes, not two
+
+Progression state was two scopes — `PlayerState` (persisted) and `SessionState` (transient) — with achievements
+and best times leaking out as special cases: `PlayerState.Reset()` deliberately skipped `UnlockedAchievements`,
+and best times lived in the ghost replay files rather than the save. We split progression into **Attempt**,
+**Playthrough** and **Profile** (defined in `CONTEXT.md`), because introducing save slots makes the third scope
+mandatory rather than a preference: Steam achievements are per-account and cannot be un-earned, so a
+per-Playthrough achievement list would permanently contradict Steam the moment a second slot exists. Best times
+follow the same argument — a completionist's record is not something starting a new game should reset.
+
+## Considered options
+
+Keeping one persisted root with a hand-maintained list of fields that survive New Game. Rejected: that is exactly
+what the old `Reset()` did, and it had already drifted — achievements survived by omission rather than by design,
+and nothing would have caught the next missed field.