fix(auto-report): scalar config bricks CLI; execvp path skips auto-draft

[CoreyRDean]

Follow-up from Codex review on PR #110 (P1 + P2).

Problem 1 (P1) — Scalar config bricks the CLI

At `lib/clauck:149`, the code assumes `auto_report` is always a mapping:

```python
mode = cfg.get("auto_report", {}).get("mode", "draft")
```

But `clauck config set auto_report draft` stores a scalar string. Once stored, any CLI invocation hits `AttributeError: 'str' object has no attribute 'get'` inside `_notify_pending_auto_reports()` — which runs from `main()` — and the CLI is effectively bricked until the user manually edits `.clauck.config.json`.

Fix

Type-guard the config read and either coerce scalar → mapping or treat non-mapping as absent. Simplest:

```python
ar = cfg.get("auto_report") or {}
if not isinstance(ar, dict):
ar = {}
mode = ar.get("mode", "draft")
```

Also consider validating config shape in `clauck config set` for known structured keys, but the read-side guard is the minimum fix to prevent bricking.

Problem 2 (P2) — Fix-path skips auto-draft

At `lib/clauck:3294`, in interactive `doctor --dry` with a non-empty `fix_instruction`, accepting the prompt executes `os.execvp(...)` to hand off to `clauck doctor --fix`. This happens before the auto-report hook runs. Since the prompt defaults to yes on Enter, the common interactive path skips autonomous reporting for exactly the cases where a fix instruction exists — the cases that most deserve a durable report.

Fix

Call `_write_auto_draft(...)` before the `os.execvp()` handoff. Reorder or add a pre-handoff write.

Acceptance

• `clauck config set auto_report draft` + any subsequent CLI command does not brick.
• Test: write scalar `auto_report` value to config, run `clauck list` (or any cmd), assert clean exit.
• Interactive doctor prompt with fix_instruction → auto-draft is queued before execvp handoff.
• Test for the reorder.