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

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

docs/adr/0002-attempt-is-a-ledger.md

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+# Attempt is a separate aggregate holding a ledger
+
+**Playthrough** and **Attempt** are separate aggregate roots rather than one root containing the other, and an
+Attempt records a *ledger* — coins found, coins spent, skills bought — rather than just a purse of coins found.
+Separate roots keeps each aggregate small and gives the Attempt its own lifecycle, since it is never persisted.
+The ledger exists so that the rule "nothing survives an Attempt unless you complete the level" applies to
+purchases too: under the previous model `RemoveCoins` drained session coins and then debited banked coins
+immediately, so buying a skill mid-level and then dying lost both the coins and the skill.
+
+## Consequences
+
+- Affordability is a cross-aggregate **read** (`attempt.CoinsFound + playthrough.Bank >= cost`). Reads may cross
+  scopes; writes may not.
+- Purchasing writes only the Attempt. The only operation touching both roots is Commit, which has exactly one
+  call site.
+- Discarding an Attempt undoes purchases rather than refunding them — under the ledger they never happened.