v0.105.0: fork-4 offsite password custody — hand-off + atomicity gate + DR inject + coord

Pairs with agent v0.77.0. StageEscrowSecret pushes the repo password to the
agent (POST /escrow/stage-secret) at offsite-enable → EscrowState="pending".
Atomicity gate: RunOffboxBackup (scheduler + handler) refuses until
EscrowState="escrowed" (operator POST /backup/offbox/confirm-escrow after the
escrow ceremony) — no un-recoverable offsite ciphertext can exist. DR:
POST /backup/offbox/inject-password pre-places a recovered 64-hex password 0600
(honored by WriteOffboxSecrets' IsNotExist guard; refuses clobber without
force). DR recipe gains non-secret offsite_restic coords (DRResticCoord); SFTP
key regenerated at DR, not escrowed. New settings.OffboxTarget.EscrowState.
Tests + atomicity & inject companion red-proofs green; UI gates pass. NOT yet
live-validated (supervised ceremony).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PSK5g6qYLknKj8u3QAFEr6

controller/internal/web/templates/backups.html

@@ -142,6 +142,14 @@
     </div>
     {{if .Offbox.LastError}}<p class="form-hint" style="color:var(--crit)">Utolsó hiba: {{.Offbox.LastError}}</p>{{end}}
     {{if .Offbox.LastWarning}}<p class="form-hint" style="color:var(--warn)">{{.Offbox.LastWarning}}</p>{{end}}
+    {{if and .OffboxConfigured (ne .Offbox.EscrowState "escrowed")}}
+    <div class="card" style="border-left:3px solid var(--warn);margin:.75rem 0;padding:.75rem 1rem">
+        <p class="form-hint" style="color:var(--warn);margin:0 0 .5rem">A NAS-mentés a kulcs letétbe helyezésére vár — a mentés addig nem fut (így nem keletkezik visszaállíthatatlan másolat). Futtasd a letéti szertartást, majd erősítsd meg.</p>
+        <form method="POST" action="/backup/offbox/confirm-escrow" style="display:inline">{{.CSRFField}}
+            <button type="submit" class="btn btn-sm">Letét megerősítése</button>
+        </form>
+    </div>
+    {{end}}
     {{if .OffboxConfigured}}
     <div class="schedule-actions" style="margin-top:1rem">
         <form method="POST" action="/backup/offbox/run" style="display:inline">{{.CSRFField}}