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

nisse-core/tests/test_render_anthropic.py

@@ -4,7 +4,7 @@ these tests pin the differences that a normalising middlebox would blur."""
 import httpx
 import pytest
 
-from nisse_core.canonical import (
+from nisse_core.log.canonical import (
     AssistantText,
     Compaction,
     StoredEvent,
@@ -12,8 +12,8 @@ from nisse_core.canonical import (
     ToolResult,
     UserMessage,
 )
-from nisse_core.llm import AnthropicPassthroughClient, LLMError
-from nisse_core.render_anthropic import (
+from nisse_core.models.llm import AnthropicPassthroughClient, LLMError
+from nisse_core.models.render_anthropic import (
     AnthropicMessagesRenderer,
     to_anthropic_tools,
 )