fix: resolve clippy warnings and formatting issues for CI

- Fix doc_markdown warnings in WhatsApp channel
- Fix needless_pass_by_value in cron, health, migration, service modules
- Fix match_same_arms in migration.rs
- Fix too_many_lines in skills/mod.rs
- Fix manual_let_else in tools/file_write.rs
- Apply cargo fmt formatting fixes

All 435 tests pass, clippy clean.

src/security/secrets.rs

@@ -194,7 +194,10 @@ impl SecretStore {
                 let _ = std::process::Command::new("icacls")
                     .arg(&self.key_path)
                     .args(["/inheritance:r", "/grant:r"])
-                    .arg(format!("{}:F", std::env::var("USERNAME").unwrap_or_default()))
+                    .arg(format!(
+                        "{}:F",
+                        std::env::var("USERNAME").unwrap_or_default()
+                    ))
                     .output();
             }