Add defensive fix in importer to auto-correct status when deleted_at present

Similar to the existing defensive fix for closed_at (lines 260-267 in multirepo.go), add a fix for the reverse case:

If an issue has deleted_at set but status != tombstone, auto-correct status to tombstone during import.

This handles corrupted data gracefully instead of failing import.

Existing pattern in `upsertIssueInTx`:
```go
// Defensive fix for deleted_at invariant: tombstones must have deleted_at
if issue.Status == types.StatusTombstone && issue.DeletedAt == nil {
    maxTime := issue.CreatedAt
    if issue.UpdatedAt.After(maxTime) {
        maxTime = issue.UpdatedAt
    }
    deletedAt := maxTime.Add(time.Second)
    issue.DeletedAt = &deletedAt
}
```

Need to add the reverse:
```go
// Defensive fix: if deleted_at is set, status must be tombstone
if issue.Status != types.StatusTombstone && issue.DeletedAt != nil {
    issue.Status = types.StatusTombstone
}
```


Test dependency child


Run bd doctor at end of bd init to verify setup

Run bd doctor diagnostics at end of bd init (after line 398 in init.go). If issues found, warn user immediately: '⚠ Setup incomplete. Run bd doctor --fix to complete setup.' Catches configuration problems before user encounters them in normal workflow.


Support wisps in nodb mode for lightweight Gas Town rigs

Enable proper wisp support in --no-db mode to allow lightweight Gas Town rigs (including HQ/Mayor) to run without SQLite overhead.

## Motivation
Gas Town HQ and simple rigs could benefit from nodb mode's simplicity. Currently wisps don't work properly in nodb mode.

## Proposed Design

### Phase 1: Session-scoped wisps
- Memory storage already has Wisp field on Issue
- Wisps exist only for the session lifetime
- Acceptable for patrol cycles that complete within a session
- Depends on: bd-9avq (fix the leak)

### Phase 2: Optional wisp persistence
- Add `.beads/wisps.jsonl` for wisp storage (gitignored)
- Load wisps from this file on nodb startup
- Save wisps to this file on nodb exit
- Wisps persist across restarts but don't sync via git

### Phase 3: Verify mol commands
- Test mol squash, burn, bond work with memory storage
- These currently check for SQLite storage type
- May need interface-based approach instead of type assertions

## Files affected
- cmd/bd/nodb.go - wisp filtering and optional persistence
- internal/storage/memory/ - verify wisp field handling
- cmd/bd/mol_*.go - verify memory storage compatibility
- .beads/.gitignore - add wisps.jsonl


Session ended: gt-beads-crew-fang