docs(R5): rewrite knowledge schema + llm-wiki for DB-native model; deprecate root inventory.yaml

Rewrote .agents/domains/knowledge/schema.md and .agents/shared/llm-wiki.md
which described the deleted Python substrate (bin/homelab, oikos/cards/,
oikos/ledger.py, root inventory.yaml, knowledge/sources/, get_page/
search_docs MCP tools). Now reflect ADR 0003: Postgres DB is the single
source of truth for structured data and narrative knowledge; seeds/*.yaml
are bootstrap+DR manifests (content-hashed via seed_versions); archive/
knowledge/ is the frozen legacy wiki; MCP search_knowledge/get_entity_
knowledge replace get_page/search_docs.

Swept substrate refs in .agents/shared/{writing-style,page-templates}.md
and .agents/domains/operations/schema.md: bare inventory.yaml ->
seeds/inventory.yaml; knowledge/sources/ -> archive/knowledge/sources/
(historical); get_changelog/oikos/ledger.py -> DB audit trail / structured
document changelog field; HERMES -> Nomos.

Root inventory.yaml (618-line Python-era file superseded 2026-07-07 by
seeds/inventory.yaml) replaced with a deprecation stub pointing to the seed
and DB. Kept as a stub rather than deleted because AGENTS.md §1/§2 still
point clients at /opt/homelab-context/inventory.yaml; full on-client path
reconciliation deferred to R13.

Flagged export gap: oikos export regenerates seeds/{ontology,inventory,
policy}.yaml but NOT seeds/knowledge.yaml — API-added knowledge lives only
in the DB until hand-edited into the seed.

VERSION 0.7.7 -> 0.7.8. Plan R5 marked done.

.agents/shared/llm-wiki.md

@@ -1,40 +1,49 @@
 # LLM Wiki — the documentation contract
 
-How the narrative documentation in this repo is organized. The pattern is borrowed from the
-`sources / wiki / index / log` model: a durable synthesized layer (`archive/knowledge/`) built on top
-of immutable evidence (`knowledge/sources/`, incident records), with pure-listing indexes and an
-append-only operations log.
+How documentation in this repo is organized. The pattern is the `sources / wiki / index / log`
+model: a durable synthesized layer built on top of immutable evidence, with pure-listing indexes and
+an append-only operations log.
 
-This contract governs the **narrative layer only**. The machine-readable substrate — `inventory.yaml`,
-`secrets/`, `scripts/`, `bin/` — is not part of the wiki and never
-moves under it. See [the knowledge schema](../domains/knowledge/schema.md) for the split.
+This contract governs the **narrative layer only**. The machine-readable source of truth — the
+Postgres database, bootstrapped from `seeds/` — is not part of the wiki and never moves under it.
+See [the knowledge schema](../domains/knowledge/schema.md) for the split, and ADR 0003 for the
+DB-native model.
 
 ## Layers
 
-- **Sources** are immutable raw material: incident records (`knowledge/sources/investigations/`), external reference
-  docs (`knowledge/sources/references/`), and the live system itself (`pct config`, `docker inspect`).
-  Read them; do not rewrite them into other sources.
-- **Wiki** (`archive/knowledge/`) is the synthesized, authoritative current-state layer: one page per
-  node (`containers/`, `vms/`, host narratives) and per cross-cutting system (`infrastructure/`). A
-  reader understands the topic from the wiki page without reading the sources.
+- **Source of truth** is the Postgres database. Structured data (entities, relationships, status,
+  metrics) and narrative knowledge (documents, investigations, runbooks) both live there, in the
+  `entities` / `relationships` / `knowledge_entities` tables. It is bootstrapped at deploy time from
+  `seeds/{ontology,inventory,policy,knowledge}.yaml` (idempotent, content-hashed via
+  `seed_versions`) and mutated at runtime via the API/MCP. `oikos export` regenerates
+  `seeds/{ontology,inventory,policy}.yaml` for version control.
+- **Sources** are immutable raw material: incident records (now `investigation` entities in the DB,
+  historically `archive/knowledge/sources/investigations/`), external reference docs, and the live
+  system itself (`pct config`, `docker inspect`). Read them; do not rewrite them into other sources.
+- **Wiki** — the synthesized, authoritative current-state layer. Today this is the set of
+  `document` entities in the DB (one per node and per cross-cutting system), queried via MCP
+  `search_knowledge` / `get_entity_knowledge`. The legacy file-based wiki is frozen at
+  `archive/knowledge/{hosts,containers,vms,infrastructure}/` for historical reference only.
 - **Index** (`index.md` / folder `README.md`) is a pure listing — every page in scope with a
   one-line summary, and nothing else. Anything the section wants to say up front goes into a page
   the index lists, not into the index.
-- **Log** (`log.md`) is append-only, recording *doc-maintenance operations* (restructures, source
-  ingests, lint sweeps) in single-line format: `## [YYYY-MM-DD] <op> | <summary>`.
+- **Log** is append-only, recording *doc-maintenance operations* (restructures, source ingests,
+  lint sweeps) in single-line format: `## [YYYY-MM-DD] <op> | <summary>`. The active log is the DB
+  audit trail; `archive/knowledge/log.md` is the frozen legacy equivalent.
 
 ## Two logs, kept distinct
 
-- **`## Changelog`** on each node/topic page records *infrastructure* changes to that node. It is
-  machine-parsed (`get_changelog`, the Oikos ledger) — keep the `### YYYY-MM-DD — title` shape.
-- **`log.md`** per area records *documentation* operations only. It never duplicates the Oikos
-  change ledger (`oikos/ledger.py`), which stays authoritative for infra changes with
-  who/what/risk/approval/verification.
+- **`## Changelog`** on each node/topic document records *infrastructure* changes to that node. It
+  is stored as a structured field on the `document` entity — keep the `### YYYY-MM-DD — title`
+  shape so it parses cleanly.
+- **Doc-maintenance logs** record *documentation* operations only. They never duplicate the
+  infrastructure changelog, which stays authoritative for infra changes with
+  who/what/risk/approval/verification (now the DB audit trail, formerly `oikos/ledger.py`).
 
 ## Rules
 
 - Wiki pages stay short and focused. A page past ~300 lines splits.
-- Pages stay flat under `wiki/<section>/` until there are enough to warrant a sub-group.
+- Pages stay flat under their section until there are enough to warrant a sub-group.
 - Every page follows [writing-style.md](writing-style.md).
 - Plans and design docs always live in the repo `plans/` folder (`plans/YYYY-MM-DD-slug.md`),
   listed in `plans/index.md`, moved to `plans/done/` on completion — never a scratch path or a chat