archive: remove entire archive/ directory and all references

archive/ contained the old narrative wiki (superseded by DB as source
of truth), hermes-plans, oikos-cards, ledger, secrets-issuance, and
SOPS backups — all Python-era artifacts with no ongoing value.

Updated all cross-references in:
- AGENTS.md, README.md
- .agents/operations/commands.md (point to docs/infrastructure/)
- .agents/shared/llm-wiki.md, page-templates.md
- .agents/domains/knowledge/schema.md, operations/schema.md
- .agents/skills/*/SKILL.md
- docs/infrastructure/*.md (removed archive link targets)
- docs-lint/SKILL.md known-baseline note

.agents/domains/operations/schema.md

@@ -8,7 +8,7 @@ exception.
 Where each kind lives: runbooks are skills under [`.agents/skills/`](../../skills/); operator
 reference (command cheatsheet, enrollment, Nomos agent) lives in
 [`.agents/operations/`](../../operations/); investigations are `investigation` entities in the DB
-(historically `archive/knowledge/sources/investigations/`); plans stay in the repo-root `plans/`
+(historically investigation entities in the DB); plans stay in the repo-root `plans/`
 folder (below).
 
 ## Plans always live in `plans/`
@@ -49,7 +49,7 @@ Incident records are `investigation` entities in the DB, linked to the entities
 `about` edges. They are **evidence sources** — written once at incident time, then back-linked from
 the changelogs of the nodes they implicate. Sections: `## Summary`, `## Timeline`, `## Root cause`,
 `## Mitigations applied`, `## Open questions`. The legacy file-based investigations live at
-`archive/knowledge/sources/investigations/` (frozen 2026-07-07); new investigations go in the DB.
+investigation entities in the DB.
 
 ## The operations log