feat(protocols): add protocols artifact convention, sys-medic protocol + CLI (WP-0002 T17-T24)

- ADR-003: protocols artifact convention (location, structure, lifecycle)
- agents/protocols/README.md: directory-level index and usage guide
- agents/protocols/sys-medic/k3s-node-health-assessment.md: full structured
  k3s node health assessment protocol (8 steps: OS baseline, process hygiene,
  memory, CPU, disk, network, k3s node state, runtime services)
- agent-sys-medic.md: add memory: enabled frontmatter, session-start/close
  protocols, node-profile memory template extensions, protocol reference in
  Default Task
- cli.py: add protocols command group (list, show); extend memory init to hint
  protocol commands for agents that have protocols

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

agents/protocols/README.md

@@ -0,0 +1,40 @@
+# Agent Protocols
+
+This directory contains **protocol runbooks** — structured, human-readable procedural documents that kaizen-agentic agents reference during structured assessments or remediation work.
+
+Protocols are distinct from agent prompts:
+- **Agent prompts** (`agents/agent-*.md`) shape AI behaviour
+- **Protocols** (`agents/protocols/<agent>/<slug>.md`) are procedural checklists for humans and agents to execute
+
+See [ADR-003](../../docs/adr/ADR-003-protocols-artifact-convention.md) for the full convention.
+
+## Structure
+
+```
+agents/protocols/
+  <agent-name>/
+    <slug>.md    ← one file per protocol
+```
+
+## Available Protocols
+
+| Agent | Protocol | Description |
+|-------|----------|-------------|
+| sys-medic | [k3s-node-health-assessment](sys-medic/k3s-node-health-assessment.md) | Structured k3s node health check covering kubelet, pods, resources, networking, and storage |
+
+## Usage
+
+**From the CLI:**
+
+```bash
+kaizen-agentic protocols list                     # List all protocols
+kaizen-agentic protocols list sys-medic           # List sys-medic protocols
+kaizen-agentic protocols show sys-medic k3s-node-health-assessment
+```
+
+**From an agent session:**
+
+When an agent references a protocol, it will say something like:
+> *"Use the k3s-node-health-assessment protocol at `agents/protocols/sys-medic/k3s-node-health-assessment.md` for this assessment."*
+
+Protocols can also be read and executed directly without an AI agent.