Stop paying for filtered log messages; sample per-event hot-path logs

SecureLogger's public wrappers evaluated their message autoclosure before
the level check inside log(), so every filtered debug message across the
codebase still paid for string interpolation - hundreds of call sites on
the per-packet/per-event hot paths. The wrappers now guard the level
first, and debug() compiles out of release builds entirely. Regression
tests verify filtered messages are never constructed.

The two heaviest per-event debug logs (NostrRelayManager inbound events,
ChatNostrCoordinator geo events) are now sampled every 100th with a
running count, so debug-enabled dev builds stop emitting hundreds of
lines per minute in busy geohashes.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

localPackages/BitLogger/Tests/LogLevelFilteringTests.swift

@@ -0,0 +1,54 @@
+import XCTest
+@testable import BitLogger
+
+/// The public logging wrappers must not evaluate their message autoclosure
+/// when the level is filtered out — hot paths log per packet/event, and
+/// building a discarded interpolated string on each call is real overhead.
+final class LogLevelFilteringTests: XCTestCase {
+    private final class EvaluationCounter {
+        var count = 0
+        func message() -> String {
+            count += 1
+            return "expensive interpolation"
+        }
+    }
+
+    private var originalLevel: SecureLogger.LogLevel!
+
+    override func setUp() {
+        super.setUp()
+        originalLevel = SecureLogger.minimumLevel
+    }
+
+    override func tearDown() {
+        SecureLogger.minimumLevel = originalLevel
+        super.tearDown()
+    }
+
+    func testFilteredDebugMessageIsNeverEvaluated() {
+        SecureLogger.minimumLevel = .info
+        let counter = EvaluationCounter()
+
+        SecureLogger.debug(counter.message())
+
+        XCTAssertEqual(counter.count, 0, "Filtered debug message should not be constructed")
+    }
+
+    func testFilteredInfoMessageIsNeverEvaluated() {
+        SecureLogger.minimumLevel = .error
+        let counter = EvaluationCounter()
+
+        SecureLogger.info(counter.message())
+
+        XCTAssertEqual(counter.count, 0, "Filtered info message should not be constructed")
+    }
+
+    func testEnabledLevelStillEvaluatesMessage() {
+        SecureLogger.minimumLevel = .debug
+        let counter = EvaluationCounter()
+
+        SecureLogger.warning(counter.message())
+
+        XCTAssertEqual(counter.count, 1, "Enabled levels must still log")
+    }
+}