refactor: ZXing对齐 — 容差50pct + 几何验证 + end-based中心 + 废弃代码清理

- detect.rs: 容差从40%提升到50% (对齐ZXing的moduleSize/2)
- detect.rs: 中心点改用ZXing end-based公式 (浮点精度, end - r4 - r3 - r2/2)
- detect.rs: 新增validate_finder_geometry()几何验证
  module_size一致性<10% + 勾股定理偏差<15%
- detect.rs: compute_finder_deviation改用base=total/7
- detect.rs: 删除废弃的estimate_finder_size函数
- perspective.rs: count_finder_hits容差对齐 (base=total/7 + 50pct)
- web/main.rs + cli/main.rs: 修复Rust 1.96新版clippy规则

cli/src/main.rs

@@ -266,7 +266,7 @@ fn build_mode(mode: &str, opts: &EncodeOpts, fb: &str) -> Result<String> {
             let pwd = opts
                 .password
                 .as_deref()
-                .or_else(|| env_pwd.as_deref())
+                .or(env_pwd.as_deref())
                 .unwrap_or("");
             Ok(text_builder::build_wifi_text(
                 s,