nisse-core: group modules into packages by architecture section

A pure move; behaviour unchanged.

- models (L9, L7): llm, catalog, probe, render, render_anthropic, context
- log (L7, L6): canonical, views
- state (L8): store (was state), reconcile, worker, cancel, dump
- knowledge (L10, L6.4): vault, memory
- conversation (L5): transport, matrix
- execution (L13): ssh (was execution), testing
- authority (P3, P4, L4): actions
- gitea, oplog, envfile stay at the top until each gains a second module.

Every import, monkeypatch target, script and doc reference rewritten.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01J5Utyfzw7gF7UhjRDEtjTk

tests/integration/conftest.py

@@ -15,7 +15,7 @@ import pytest
 
 from nisse_core.envfile import load_env_file
 from nisse_core.gitea import GiteaClient
-from nisse_core.llm import AnthropicPassthroughClient, LiteLLMClient
+from nisse_core.models.llm import AnthropicPassthroughClient, LiteLLMClient
 from nisse_dev.config import AgentConfig
 
 REPO = Path(__file__).resolve().parents[2]