docs(P00): research findings — Docker-in-LXC, 10 questions resolved (conf 0.80-0.95)

RESEARCH.md: 648 lines (10 research questions, topology, risks, reuse table)
ARCHITECTURE.md: +v0.2 deployment section (Docker-in-LXC, image build, secrets, sizing)
PERSONAS.md: 5 active personas (devops-engineer added, frontend-engineer deactivated)

Key findings:
- nesting=1 sufficient for Docker-in-LXC (conf 0.85)
- CT sizing: 4GB/16GB (build-inside-CT, conf 0.80)
- FastAPI StaticFiles at / after API routes, no SPA fallback (conf 0.95)
- Multi-stage: node:22-slim → python:3.12-slim, CMD python -m server (conf 0.90)
- Systemd: Type=simple, docker compose up (foreground), TimeoutStartSec=300 (conf 0.85)
- Health-check timeout bumped 180s→300s for Docker build (conf 0.90)

---ci---
project: praxis
phase: 0
milestone: v0.2
status: research
---/ci---

.ciagent/CHECKPOINT.json

@@ -1,14 +1,20 @@
 {
   "phase": 0,
-  "stage": "clarify",
+  "stage": "research",
   "milestone": "v0.2",
   "phase_role": "pre_execution",
   "attempts": 0,
-  "updated_at": "2026-08-01T14:05:00Z",
-  "clarifications": {
-    "D-027": "VMID=auto (fresh allocation)",
-    "D-028": "Docker installed inside CT via apt",
-    "D-029": "Image built inside CT (clone repo + docker build)",
-    "D-030": "CT network=vmbr0 DHCP only (no proxy/TLS)"
+  "updated_at": "2026-08-01T14:15:00Z",
+  "research_confidence": {
+    "docker_in_lxc": 0.85,
+    "build_inside_ct": 0.80,
+    "fastapi_staticfiles": 0.95,
+    "dockerfile_design": 0.90,
+    "firstboot_hook": 0.85,
+    "secret_injection": 0.90,
+    "health_check": 0.90,
+    "systemd_unit": 0.85,
+    "ct_sizing": 0.80,
+    "testing": 0.90
   }
 }