docs: add service README.md files + update AGENTS.md decisions

- Create README.md for 25+ service modules with container info, API surface, storage
- Document attestor-tileproxy separation rationale (air-gap network isolation)
- Document opsmemory-advisoryai separation rationale (resource isolation, blast radius)
- Update Timeline AGENTS.md with merged indexer info

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/Notify/README.md

@@ -0,0 +1,17 @@
+# Notify
+
+**Container(s):** stellaops-notify-web
+**Slot:** 29  |  **Port:** 8080  |  **Consumer Group:** notify
+**Resource Tier:** medium
+
+## Purpose
+Notify is the notification routing and delivery service for the Stella Ops platform. It manages notification channels, templates, preferences, routing rules, and delivery pipelines with plugin-based channel support. It handles alert dispatching, escalation workflows, and notification lifecycle tracking with PostgreSQL-backed persistence.
+
+## API Surface
+- `notify` (via Router) — notification submission, channel management, preference CRUD, template management, delivery status, routing rules, audit trail
+
+## Storage
+PostgreSQL schema `notify` (via `Postgres:Notify:ConnectionString`); plugin-based channel storage
+
+## Background Workers
+- None (web-only service; delivery is synchronous or plugin-delegated)