docs: add ECC update/upgrade instructions

Covers pulling latest, backing up customizations (model tiers, hook fixes),
re-running installer, and re-applying changes that get overwritten.

ecc-setup-guide.md

@@ -191,3 +191,63 @@ for f in ~/.claude/agents/{code,python,typescript,rust,go,java,kotlin,cpp,flutte
   sed -i 's/^model: sonnet/model: opus/' "$f"
 done
 ```
+
+## Updating ECC
+
+The installer overwrites all files in `~/.claude/`, so updating is straightforward — but custom changes (model tiers, hook fixes) will be lost. Back them up first.
+
+### Update steps
+
+**1. Pull the latest version:**
+
+**Windows (PowerShell):**
+```powershell
+cd C:\Users\<USERNAME>\everything-claude-code
+git pull
+npm install
+```
+
+**macOS/Linux (Bash):**
+```bash
+cd ~/everything-claude-code
+git pull
+npm install
+```
+
+**2. Back up your customizations:**
+```bash
+# Save agent model overrides
+grep -l 'model: opus' ~/.claude/agents/*.md > /tmp/ecc-opus-agents.txt
+
+# Save patched hook files
+cp ~/.claude/skills/continuous-learning-v2/hooks/observe.sh /tmp/observe.sh.bak
+cp ~/.claude/skills/continuous-learning-v2/scripts/detect-project.sh /tmp/detect-project.sh.bak
+cp ~/.claude/skills/continuous-learning-v2/config.json /tmp/cl-config.json.bak
+```
+
+**3. Re-run the installer:**
+
+**Windows (PowerShell):**
+```powershell
+.\install.ps1 python typescript
+```
+
+**macOS/Linux (Bash):**
+```bash
+./install.sh python typescript
+```
+
+**4. Re-apply customizations:**
+
+- Re-apply agent model tiers (Step 6 above)
+- Re-apply the three Windows hook fixes (gotchas 6–8 above)
+- Re-enable observer in `config.json` (`"enabled": true`)
+- Re-add `Bash` to planner and architect tools (Step 3 above)
+
+### Check current version
+
+```bash
+cat ~/.claude/plugin.json | grep version
+# or from the repo:
+cat ~/everything-claude-code/VERSION
+```