Manage BetterStack dashboard queries + alerts in git

## Background

The SQL queries and alerts behind our two main dealbot dashboards live **only** in the BetterStack UI. Than means:
- No version history – we can't see what a query looked like last week or who change it.
- No review – query/alert changes ship with nobody else looking.
- No diffing or easy revert.

## Proposal (deliberately minimal)

Mirror the chart queries and alerts in this repo and gate changes behind a PR. No new infra or automation right not.

1. **One-time-export** of all chart queries + alerts from BetterStack into the repo.
2. **Every change** to a chart query or alert goes through a PR with **1 approval** from a teammate.
3. After approval: **apply the change in BetterStack, then merge** the PR.

The win: reviewable, versioned, revertable queries and alerts.

## In scope

The two main dashboards:

| Dashboard | ID | Charts | Source |
|---|---|---|---|
| Operational | `618457` | 17 | Infra Prod |
| Provider | `624265` | 49 | Infra Staging |

Both their chart SQL **and** their alerts.

## Proposed repo layout

```
docs/dashboards/
operational/
charts/.sql
alerts/.json
provider/
charts/.sql
alerts/.json
```

- One `.sql` file per chart query.
- One JSON file per alert (threshold / condition / notification target diffs cleanly as structured data, not prose).
- Chart/alert files keyed by their stable Better Stack numeric ID (in the file or a small index) so we always know which live object a file maps to.

## Workflow

```
open PR → 1 teammate approves → apply change in Better Stack → merge
```

`main` always reflects the last approved-and-applied state.

## Tasks

- [ ] Export Operational + Provider dashboard charts -> `charts/` & alerts -> `alerts/`
- [ ] Add a per-file mapping to Better Stack chart/alert IDs
- [ ] Document the PR-gated change workflow in `docs/dashboards/README.md`

Start in BetterStack by identifying the charts and alerts for dashboards 618457 and 624265, then export them into docs/dashboards/ using the proposed operational and provider layout. Add stable Better Stack chart and alert IDs per file, and document the one-approval workflow in docs/dashboards/README.md. Done means all 66 charts and their alerts are represented and the workflow is documented.

Written by the indexing model from the issue text.