Remove dead code found by full Periphery audit; add scan config + advisory CI (#1410)

Periphery 3.7.4 audit of both schemes (macOS + iOS, intersected so
platform-specific code is never touched), with test targets indexed and
the share extension built. 277 dead declarations removed or demoted:
dead forwarding wrappers (ChatViewModel+Nostr/+PrivateChat), removed-
feature remnants (autocomplete command suggestions, back-swipe tuning,
MediaSendError, GeohashParticipantTracker), unused Tor dormancy
bindings, assign-only properties, unused parameters (renamed to _), and
redundant public accessibility. 13 orphaned localization keys deleted
across all 29 locales (old pre-#1392 location-notes UI, app_info
warnings).

Two real tests were flagged as unused because they never ran: Swift
Testing methods missing @Test (NostrProtocolTests.
testAckRoundTripNIP44V2_Delivered, NotificationStreamAssemblerTests.
testAssemblesCompressedLargeFrame). Re-armed both; they pass.

Deliberately kept, now recorded in .periphery.baseline.json: iOS-only
code invisible to the CI macOS scan, C FFI signatures, keep-alive
NWPathMonitor reference, InboundEventKey.eventID (dedup semantics),
wifiBulk capability bit (reserved for Wi-Fi bulk work, used by
BitFoundation package tests), and the String secureClear cluster
(exercised by package tests).

New: .periphery.yml config and an advisory Dead Code CI job (mirrors
the SwiftLint precedent from #1361) that fails on findings not in the
committed baseline.

Verified: full macOS app suite, BitFoundation (119) and BitLogger (13)
package tests green; periphery scan --strict exits clean.

Co-authored-by: jack <jackjackbits@users.noreply.github.com>
Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

localPackages/Arti/Sources/TorManager.swift

@@ -30,12 +30,6 @@ private func arti_bootstrap_progress() -> Int32
 @_silgen_name("arti_bootstrap_summary")
 private func arti_bootstrap_summary(_ buf: UnsafeMutablePointer<CChar>, _ len: Int32) -> Int32
 
-@_silgen_name("arti_go_dormant")
-private func arti_go_dormant() -> Int32
-
-@_silgen_name("arti_wake")
-private func arti_wake() -> Int32
-
 /// Arti-based Tor integration for BitChat.
 /// - Boots a local Arti client and exposes a SOCKS5 proxy
 ///   on 127.0.0.1:socksPort. All app networking should await readiness and
@@ -83,7 +77,6 @@ public final class TorManager: ObservableObject {
     private var bootstrapMonitorStarted = false
     private var pathMonitor: NWPathMonitor?
     private var isAppForeground: Bool = true
-    private var isDormant: Bool = false
     private var lastRestartAt: Date? = nil
     private var startedAt: Date? = nil  // Tracks initial startup time for grace period
     private(set) var allowAutoStart: Bool = false
@@ -102,7 +95,6 @@ public final class TorManager: ObservableObject {
         }
         guard !didStart else { return }
         didStart = true
-        isDormant = false
         isStarting = true
         startedAt = Date()  // Track startup time for grace period
         SecureLogger.debug("TorManager: startIfNeeded() - startedAt set", category: .session)
@@ -353,7 +345,6 @@ public final class TorManager: ObservableObject {
             }
 
             await MainActor.run {
-                self.isDormant = false
                 self.isReady = false
                 self.socksReady = false
                 self.bootstrapProgress = 0
@@ -383,7 +374,6 @@ public final class TorManager: ObservableObject {
             self.bootstrapProgress = 0
             self.bootstrapSummary = ""
             self.isStarting = true
-            self.isDormant = false
             self.lastRestartAt = Date()
         }