feat: add Honcho memory provider with PostgreSQL + pgvector stack

Add Honcho (https://github.com/plastic-labs/honcho) as a self-hosted
memory infrastructure for stateful AI agents.

Changes:
- ai/honcho/Dockerfile: multi-stage build from Honcho GitHub source
- ai/honcho/init.sql: CREATE EXTENSION vector for pgvector
- ai/compose.yml: add honcho-db (pgvector/pgvector:pg17-trixie) and
  honcho services with ai_backend/ai_net networking and Traefik labels
- build/honcho/config.toml: pre-configured for Ollama embeddings
  (nomic-embed-text via http://ollama:11434/v1), deriver/summary/dream
  disabled by default
- env/.env.example.honcho: sample env vars (HONCHO_DB_PASSWORD,
  LLM_OPENAI_API_KEY)

Usage:
  cp env/.env.example.honcho .env  # edit secrets
  mkdir -p /mnt/HoardingCow_docker_data/Honcho
  cp build/honcho/config.toml /mnt/HoardingCow_docker_data/Honcho/config.toml
  docker compose -f ai/compose.yml up honcho

build/honcho/config.toml

@@ -0,0 +1,93 @@
+# Honcho Configuration
+# Pre-configured for self-hosted deployment with Ollama embeddings.
+# Mount this file at /app/config.toml in the Honcho container.
+#
+# Environment variables override these values at runtime
+# (e.g. DB_CONNECTION_URI, DERIVER_*).
+
+[app]
+LOG_LEVEL = "INFO"
+NAMESPACE = "honcho"
+SESSION_OBSERVERS_LIMIT = 10
+GET_CONTEXT_MAX_TOKENS = 16384
+EMBED_MESSAGES = true
+
+[db]
+# Connection URI is set via environment variable DB_CONNECTION_URI
+SCHEMA = "public"
+POOL_SIZE = 10
+MAX_OVERFLOW = 20
+POOL_TIMEOUT = 30
+POOL_RECYCLE = 300
+POOL_PRE_PING = true
+POOL_USE_LIFO = true
+SQL_DEBUG = false
+
+[auth]
+USE_AUTH = false
+
+[llm]
+DEFAULT_MAX_TOKENS = 4096
+
+[embedding]
+VECTOR_DIMENSIONS = 768
+MAX_INPUT_TOKENS = 8192
+MAX_TOKENS_PER_REQUEST = 2048
+
+[embedding.model_config]
+transport = "openai"
+model = "nomic-embed-text:latest"
+
+[embedding.model_config.overrides]
+base_url = "http://ollama:11434/v1"
+# Ollama does not require an API key; env var must be set to non-empty string
+api_key_env = "LLM_OPENAI_API_KEY"
+
+[deriver]
+ENABLED = false
+WORKERS = 1
+POLLING_SLEEP_INTERVAL_SECONDS = 1.0
+STALE_SESSION_TIMEOUT_MINUTES = 5
+DEDUPLICATE = true
+LOG_OBSERVATIONS = false
+
+[deriver.model_config]
+transport = "openai"
+model = "qwen3.6:27b-q4_K_M"
+
+[deriver.model_config.overrides]
+base_url = "http://ollama:11434/v1"
+api_key_env = "LLM_OPENAI_API_KEY"
+
+[summary]
+ENABLED = false
+
+[summary.model_config]
+transport = "openai"
+model = "qwen3.6:27b-q4_K_M"
+
+[summary.model_config.overrides]
+base_url = "http://ollama:11434/v1"
+api_key_env = "LLM_OPENAI_API_KEY"
+
+[dream]
+ENABLED = false
+
+[dialectic]
+MAX_OUTPUT_TOKENS = 4096
+MAX_INPUT_TOKENS = 16384
+
+[cache]
+ENABLED = false
+
+[vector_store]
+TYPE = "pgvector"
+
+[metrics]
+ENABLED = false
+
+[telemetry]
+ENABLED = false
+
+[sentry]
+ENABLED = false