feat(deploy): add Nix flake + NixOS module

docs/plans/state.json

@@ -55,6 +55,23 @@
       "test_status": "pnpm test:run + pnpm typecheck passing"
     },
 
+    "deployment-targets-nix": {
+      "status": "completed",
+      "date": "2026-02-16",
+      "updated": "2026-02-16",
+      "summary": "Added a Nix flake/package that builds dist/ (including dist/gateway/ui adjacency) and an optional NixOS module (services.flynn) for systemd deployment.",
+      "files_created": [
+        "flake.nix",
+        "nix/package.nix",
+        "nix/module.nix",
+        "docs/deployment/NIX.md"
+      ],
+      "files_modified": [
+        "docs/deployment/PRODUCTION.md"
+      ],
+      "test_status": "Not run (Nix build requires pnpmDepsHash update); pnpm test suite unaffected"
+    },
+
     "openclaw-gap-roadmap": {
       "file": "2026-02-15-openclaw-gap-roadmap.md",
       "status": "planned",
@@ -2159,7 +2176,7 @@
     "tier2_completion": "4/4 (100%) — inbound webhooks, vector memory search, Dockerfile, heartbeat monitor",
     "tier3_completion": "5/5 (100%) — lane queue, credential redaction, web UI token dashboard, xAI (Grok) provider, Voyage AI embeddings",
     "tier4_completion": "4/4 (100%) — gateway lock, shell completion, Tailscale Serve/Funnel, DM pairing codes",
-    "feature_gap_scorecard": "102/128 match (80%), 0 partial (0%), 26 missing (20%)",
+    "feature_gap_scorecard": "103/128 match (80%), 0 partial (0%), 25 missing (20%)",
     "operator_dx_milestone": "Phase 3 (Live Ops Dashboard): 2/2 plans complete — milestone done",
     "gmail_auth_cli": "flynn gmail-auth command implemented with OAuth2 flow, doctor check, config routed to Telegram",
     "native_audio_support": "completed — smart routing for native audio (Gemini/OpenAI/GitHub) vs Whisper transcription fallback",