refactor: move diagnostics into each skill's own directory

Replace shared _shared/diagnostics.md with dedicated diagnostics.md
files in setup/ and update-nanoclaw/. Each contains only the event
types relevant to that skill. References updated to local links.

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

.claude/skills/setup/SKILL.md

@@ -220,4 +220,4 @@ Tell user to test: send a message in their registered chat. Show: `tail -f logs/
 
 ## Diagnostics (Optional)
 
-After completing all steps above, read and follow `.claude/skills/_shared/diagnostics.md`.
+After completing all steps above, read and follow [diagnostics.md](diagnostics.md).

.claude/skills/setup/diagnostics.md

@@ -0,0 +1,81 @@
+# Diagnostics (end-of-setup instructions)
+
+Follow these steps **after all other setup steps are complete**.
+
+## 1. Collect events
+
+Build the list of events to send:
+
+1. If channel skills were invoked during setup (e.g., `/add-telegram`), add a `skill_applied` event for each.
+2. Add a `setup_complete` event for setup itself.
+
+A `/setup` with no channels produces just `setup_complete`.
+
+## 2. Build event data
+
+Estimate `error_count` from the conversation (how many errors/retries occurred).
+
+**For `setup_complete`:**
+```json
+{
+  "channels_selected": ["whatsapp", "telegram"],
+  "error_count": 0,
+  "failed_step": null,
+  "exit_code": null
+}
+```
+- `channels_selected`: which channels the user chose to install
+- `failed_step`: if setup failed, which step (environment / container / groups / register / mounts / service / verify)
+- `exit_code`: if a step failed, its exit code
+
+**For each `skill_applied`:**
+```json
+{
+  "skill_name": "add-telegram",
+  "is_upstream_skill": true,
+  "conflict_files": ["package.json", "src/index.ts"],
+  "error_count": 0
+}
+```
+- `skill_name`: upstream skill name, or `"custom"` for non-upstream skills
+- `conflict_files`: filenames with merge conflicts (the script gates these against upstream)
+
+## 3. Dry run all events
+
+For **each** event, run with `--dry-run` to get the payload:
+
+```bash
+npx tsx scripts/send-diagnostics.ts --event <event_type> --success --data '<json>' --dry-run
+```
+
+Use `--failure` instead of `--success` if that particular skill/step failed.
+
+If **any** dry-run produces no output, the user has opted out permanently — skip the rest.
+
+## 4. Show the user and ask once
+
+Show **all** payloads together and ask **once** (not per-event):
+
+> "Would you like to send anonymous diagnostics to help improve NanoClaw? Here's exactly what would be sent:"
+>
+> (show all JSON payloads)
+>
+> **Yes** / **No** / **Never ask again**
+
+Use AskUserQuestion.
+
+## 5. Handle response
+
+- **Yes**: Send **all** events (run each command without `--dry-run`):
+  ```bash
+  npx tsx scripts/send-diagnostics.ts --event <event_type> --success --data '<json>'
+  ```
+  Confirm: "Diagnostics sent (N events)." or "Diagnostics sent." if only one.
+
+- **No**: Do nothing. User will be asked again next time.
+
+- **Never ask again**: Run:
+  ```bash
+  npx tsx -e "import { setNeverAsk } from './scripts/send-diagnostics.ts'; setNeverAsk();"
+  ```
+  Confirm: "Got it — you won't be asked again."