Apply code-review fixes: identity/pagination, load races, TLS pin, leaks

Addresses a multi-agent code review (26 confirmed findings + a URLSession
leak) across correctness, concurrency, security, and cleanup:

- MongoDocument.id: deterministic fallback (was UUID() on every access) to stop
  SwiftUI List/ForEach identity churn; getAll pagination drives its cursor off
  the real _id via documentId, so a missing _id stops paging instead of looping
  on a fabricated cursor.
- View models: per-load generation guard (+ captured-tab guard on ONU detail)
  so a cancelled or overlapping load can't commit stale results or land data on
  the wrong tab.
- JSONValue.intValue: guard Int(d) against NaN/inf/out-of-range (crash).
- ServerTrustEvaluator: hash the real SubjectPublicKeyInfo (prepend the
  algorithm-specific ASN.1 SPKI header) so a standard openssl-captured
  public-key pin actually matches; unknown key types fail closed.
- AppEnvironment.configure: clear stale cookies + Keychain creds on host change.
- FirmwareFile.isCompatible: empty metadata no longer passes as compatible-for-all.
- APIClient: invalidate URLSession on deinit (per-configure/probe leak).
- Dashboard best-effort sections keep last-good on transient failure; unified
  optical thresholds; LoginView prefill-once; populatedBuckets unique ForEach id;
  Format rounding rollover; dead-code/docstring/dedup cleanups.

Verification pending on the Mac (no Swift toolchain on the Linux dev box).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

LoginView.swift

@@ -7,6 +7,7 @@ struct LoginView: View {
     @State private var password = ""
     @State private var remember = true
     @State private var phase: LoadPhase = .idle
+    @State private var didPrefill = false
 
     var body: some View {
         NavigationStack {
@@ -56,6 +57,11 @@ struct LoginView: View {
                 }
             }
             .onAppear {
+                // Prefill from the Keychain ONCE — onAppear fires again when the
+                // user returns from Settings, and re-running this would wipe any
+                // credentials they'd already typed.
+                guard !didPrefill else { return }
+                didPrefill = true
                 email = env.savedEmail ?? ""
                 password = env.savedPassword ?? ""
             }