db as source of truth: wiki→seeds, archive old artifacts, knowledge ingestion

- Migrations 010 (content_hash) + 011 (search tsvector column)
- new: internal/knowledge/seed.go — knowledge seed ingest engine
- new: internal/httpapi/knowledge.go — SearchKnowledge + GetEntityKnowledge
- wire knowledge ingest into oikos seed pipeline
- convert all 36 wiki docs + 6 investigations + 12 runbooks → seeds/knowledge.yaml
- archive: knowledge/wiki/→archive/, oikos/cards/→archive/, .hermes/plans/→archive/
- delete: 9 superseded Python kernel files, ledger/, mcp/build_host_files.py
- remove empty knowledge/ directory tree

archive/knowledge/index.md

@@ -0,0 +1,14 @@
+# Knowledge
+
+The durable, authoritative current-state documentation of the homelab: one page per node and per
+cross-cutting system, synthesized from live state and evidence. Structure and rules are in
+[the knowledge schema](../.agents/domains/knowledge/schema.md).
+
+| Section | What it covers |
+|---------|----------------|
+| [wiki/hosts/](wiki/hosts/index.md) | Proxmox host narratives — `hubris`, `strong`. |
+| [wiki/containers/](wiki/containers/index.md) | LXC fleet — one page per container, plus the master table and archaeology. |
+| [wiki/vms/](wiki/vms/index.md) | Virtual machines — ZimaOS, Home Assistant OS. |
+| [wiki/infrastructure/](wiki/infrastructure/index.md) | Cross-cutting systems — DNS, ingress, mesh, storage, auth, monitoring, generated topology. |
+| [sources/](sources/index.md) | External reference docs and the pointer to incident evidence. |
+| [GLOSSARY.md](GLOSSARY.md) | Term definitions. |