Base BSD Anchor Repair

Actually cleaning up and repairing the citation error adjudicated in document 20. The precise statement of the v0.3 problem: the original text of Banwait–Huang's historical review is "Miller verified full BSD for **most** rank 0/1 curves below conductor 5000"—the keyword is most, not all—so one cannot directly infer that Miller himself had verified 696.e1 just because $696<5000$. The document switches to the precise correct source: Creutz–Miller, "Second Isogeny Descents and the BSD Conjectural Formula" Theorem 1.1; this theorem **unconditionally** gives $N<5000,\ r_{\rm an}\le1\Rightarrow\text{full BSD}$—not "most," but universal. And 696.e1 exactly satisfies $N=696,\ r_{\rm an}=0$, so full $\operatorname{BSD}(E)$ holds, especially $\operatorname{BSD}(E,2)$. The document finally emphasizes that this is a strict source-level repair, no longer relying on the circular inference of "analytic Sha masquerading as actual Sha"—echoing the trap deliberately avoided from the very beginning in document 15, confirming once again here that the entire anchor is clean.