feat(cc-013): add auto memory companion repo with three exercises

Companion repo for CC-013. Covers triggering memory, structuring
MEMORY.md with index and topic files, and proving cross-session
persistence shapes Claude behavior.

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

exercises/01-trigger-memory.md

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+# Exercise 01: Trigger Memory
+
+**Concept:** Auto Memory (CC-013)
+**Level:** Basic
+**Time:** ~10 minutes
+
+---
+
+## Objective
+
+Tell Claude something to remember, verify the memory file was created,
+and confirm it survives a new session.
+
+This is your first hands-on contact with auto memory. No prior experience
+with Claude Code memory required.
+
+---
+
+## Before You Start
+
+Confirm you have:
+
+- [ ] Claude Code v2.1.59 or later installed (`claude --version` prints a version)
+- [ ] This repo cloned and open in Claude Code
+- [ ] Started Claude Code in this directory (`claude`)
+
+---
+
+## Instructions
+
+**Step 1:** Start Claude Code in this directory.
+
+```bash
+cd claude-code-auto-memory
+claude
+```
+
+**Step 2:** Paste this prompt into Claude Code:
+
+```
+Remember that I prefer 2-space indentation and single quotes in TypeScript.
+```
+
+Claude will confirm the preference and save it to memory. You should see
+a tool call to write a file under `~/.claude/projects/`.
+
+**Step 3:** Find the memory file that was just created.
+
+Paste this into Claude Code:
+
+```
+Where did you save that memory? Show me the path and the file contents.
+```
+
+Claude will tell you the exact path. It will be somewhere under:
+
+```
+~/.claude/projects/<project-hash>/memory/
+```
+
+The `<project-hash>` is a deterministic hash of the project directory path.
+You can also find it yourself:
+
+```bash
+ls ~/.claude/projects/
+```
+
+Look for a directory that corresponds to this repo. Open the memory file
+inside it and read what was saved.
+
+**Step 4:** Start a new session and test recall.
+
+In Claude Code, type `/clear` to start a fresh conversation. Then paste:
+
+```
+What are my TypeScript preferences?
+```
+
+Claude should recall 2-space indentation and single quotes without you
+repeating them.
+
+---
+
+## Expected Output
+
+After completing the steps above, you should see:
+
+- A new file in `~/.claude/projects/<project-hash>/memory/` containing
+  your TypeScript preferences
+- Claude confirming the memory was saved during Step 2
+- After `/clear`, Claude recalling both preferences without any prompt
+
+If Claude says it has no preferences on file, check that you are in the
+same directory as Step 1. The project hash is derived from the directory
+path, so a different working directory means a different memory store.
+
+---
+
+## What You Learned
+
+- **"Remember" is the trigger:** Phrases like "remember that" or "save this"
+  cause Claude to write a memory file explicitly
+- **Project-scoped storage:** Memories are stored per project, not globally,
+  so different projects have separate memory stores
+- **Machine-local:** The memory files are on your machine only. They are not
+  in git and not shared across machines.
+
+---
+
+## Next
+
+Ready to go further? Move to [Exercise 02: Structure Memory](./02-structure-memory.md).