fix: resolve all clippy warnings and fix test compilation errors

Address clippy pedantic/all lints: format_push_string in sqlite memory,
match_same_arms and match_wildcard_for_single_variants in anthropic
provider and prometheus observer, option_as_ref_cloned in main. Fix
pre-existing test compilation errors in gateway (missing max_keys arg
and trust_forwarded_headers field) and memory_store (missing security
arg). Add .worktrees/ to gitignore.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/memory/sqlite.rs

@@ -6,7 +6,7 @@ use async_trait::async_trait;
 use chrono::Local;
 use parking_lot::Mutex;
 use rusqlite::{params, Connection};
-use std::fmt::Write;
+use std::fmt::Write as _;
 use std::path::{Path, PathBuf};
 use std::sync::mpsc;
 use std::sync::Arc;

src/observability/prometheus.rs

@@ -197,6 +197,10 @@ impl Observer for PrometheusObserver {
             } => {
                 self.errors.with_label_values(&[component]).inc();
             }
+            ObserverEvent::ToolCallStart { .. }
+            | ObserverEvent::TurnComplete
+            | ObserverEvent::LlmRequest { .. }
+            | ObserverEvent::LlmResponse { .. } => {}
         }
     }