Add AI Council architecture: Tier 2/3/Graph implementation + Integration Plan

Architecture (Agent 1):
- hermes_memory/tier2/{schema,facts,entities,relations,timeline}.py
- hermes_memory/tier3/{backend,chroma_backend,embedder}.py
- hermes_memory/graph/nx_store.py
- hermes_memory/api/memory_api.py (unified API)
- hermes_memory/cron/{consolidate,embed_queue,graph_refresh,prune}.py
- hermes_memory/config.py + pyproject.toml

Integration Plan (Agent 3):
- INTEGRATION_PLAN.md: Memory Provider Plugin strategy
- Hermes Core needs minimal changes
- sync_turn() + prefetch() hooks
- Skills integration via nextlevel_search/remember

Auto-Extraction (Agent 2):
- ARCHITECTURE.md: Full extraction pipeline docs
- Chunking, Pre-Filter, LLM Prompts, Classification
- Entity-Linking, Temporal Reasoning, Deduplication

All files: Python syntax checked, ECC standards applied.

hermes_memory/tier3/__init__.py

@@ -0,0 +1,7 @@
+"""Tier 3 — Semantic Memory (Qdrant / Chroma)."""
+
+from hermes_memory.tier3.backend import VectorBackend, SearchResult
+from hermes_memory.tier3.chroma_backend import ChromaBackend
+from hermes_memory.tier3.embedder import LocalEmbedder
+
+__all__ = ["VectorBackend", "SearchResult", "ChromaBackend", "LocalEmbedder"]