Merge the three repositories into one monorepo

nisse-core's history becomes the repo root; the spec moves to docs/ at
top level; nisse-dev and nisse-ops fold in as package directories, their
seed histories (pointer files only) discarded. Pointer READMEs and
CLAUDE.mds are rewritten for in-tree paths.

Rationale: for a solo operator the three-repo split tripled admin
surface (tokens, CI, webhooks, permissions, backups) and imposed a
version-pinning contract on nisse-core, while the repo boundary was
never a trust boundary — the VM is. The spec's Part H is updated in the
next commit to record the decision.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

CLAUDE.md

@@ -0,0 +1,9 @@
+# Nisse
+
+Monorepo for two self-hosted AI agents (`nisse-dev`, `nisse-ops`) over a shared
+library (`nisse-core`), one package per directory.
+
+**Read the architecture before making design decisions.** The system-level
+specification is `docs/Architecture-Build-Spec.md`. Requirements that look like
+free choices — gating structure, state durability, LLM access paths, permission
+policy — are usually settled there.