revert(vds-nftables): restore original config — T3 fix needs discussion

Owner request 2026-10-10: 'отмени вообще правки файрволла, верни
пока какие были до твоих работ. это требует обсуждения, потому
что по прежнему ничего не работает, сайт не открывается,
reality не работает.'

This reverts 5 T3 code commits + 2 T3 doc commits:
  5796786 fix(vds-nftables): apply Option A
  3deaa75 fix(vds-nftables): remove allowPing
  4dc4849 fix(vds-nftables): open SSH on all interfaces
  2649e2f fix(vds-nftables): open port 80
  51ea19a fix(vds-nftables): open port 8443
  677d39e docs(T3): note correction
  fafd3e2 docs(T3): mark nftables fix as applied

Restored:
- configurations/vds.nix → original from 61b3724 (firewall.enable = true,
  firewall.interfaces.tailscale0.allowedTCPPorts = [22], nftables with
  SYN rate-limit on {80,443})
- .agent/tasks/manifest.json T3 → status = 'pending' (was 'completed')
- .agent/decisions/index.json T3-A → status = 'proposed' (was 'accepted')

The proposal .agent/decisions/proposals/vds-nftables-fix.md is NOT
removed — it's still a proposal for future discussion, just not
applied. nft list ruleset on otreca will return to the original
(firewall-managed) state after rebuild.

T3 needs proper discussion with owner before re-applying. The
issues observed (site not opening, reality not working) need
diagnostic before any new fix attempt.

.agent/decisions/index.json

@@ -27,15 +27,16 @@
     {
       "id": "T3-A",
       "title": "nftables fix для otreca (R1.6: явная policy drop, убрать firewall/nftables конфликт, SSH только на tailscale0)",
-      "status": "accepted",
-      "date": "2026-10-10",
+      "status": "proposed",
+      "date": "2026-10-09",
       "files": [
-        ".agent/decisions/proposals/vds-nftables-fix.md",
-        "configurations/vds.nix"
+        ".agent/decisions/proposals/vds-nftables-fix.md"
       ],
       "tags": ["nftables", "vds", "otrecа", "security", "R1.6", "T3"],
       "task": "T3",
-      "notes": "Applied 2026-10-10 via nixos-rebuild switch on otreca. Verified live: nft list ruleset = policy drop + 5 accepts, iptables empty, SSH via Tailscale works, Xray REALITY on 443 listening."
+      "blocked_by": [
+        "user: SSH-доступ на otreca должен быть восстановлен до apply"
+      ]
     }
   ]
 }