fix: make Nomos actually provision LXCs from chat (pct_create + web fetch)

Root cause of "asks permission but never acts": the approved pct_create
execution failed to parse because the LLM emitted `"privileged":0` /
`"nesting":1` (numbers) into strict `bool` fields, so the container was
never created. Compounded by a hardcoded template name (debian-13.0-1)
that no longer exists on the host, and no way for the agent to read the web.

- flexBool: accept 0/1, "true", bool for privileged/nesting (the exact prod failure)
- pct_create template pre-flight: list host cache, validate/auto-pick newest debian
- pct_create services[] + post_install: one approval provisions a working service
- new http_get MCP tool (sanitized, size-capped, SSRF-guarded) — agent can read repos/sites
- request_execution description: target=host, full JSON schema + example
- SOUL.md: agent CAN fetch the web; prefer one-step provisioning
- default model deepseek-v4-flash -> v4-pro; maxIterations 15 -> 25
- unit tests for flexBool, template resolve, pkg sanitize, HTML sanitize + SSRF block

Verified live on host:strong with a throwaway VMID 999: template auto-resolved,
container created + booted, services installed, post_install ran, then destroyed.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

compose/nomos/Dockerfile

@@ -19,7 +19,7 @@ COPY nomos/ /app/nomos/
 ENV NOMOS_MCP_URL=http://api:8090/mcp
 ENV NOMOS_AGENT_SLUG=agent:nomos
 ENV NOMOS_LISTEN=:8092
-ENV NOMOS_MODEL=deepseek/deepseek-v4-flash
+ENV NOMOS_MODEL=deepseek/deepseek-v4-pro
 
 EXPOSE 8092