[1.x Bug] Metric in an installed package links to its in-model `semantic_model` under the ROOT project namespace

### Is this a new bug in dbt-core?

- [x] I believe this is a new bug in dbt-core
- [x] I have searched the existing issues, and I could not find an existing issue for this bug

### Current Behavior

When an installed package defines a semantic model + metrics via the in-model spec (`models[].semantic_model + inline models[].metrics`), dbt Core resolves the metric's dependency on its generated semantic model under the ROOT project namespace instead of the package's, so `compile`/`ls` fails:

```
   Compilation Error
     'metric.ad_reporting.active_ads' depends on 'semantic_model..ad_report' which is not in the graph!
```

The same project compiles successfully with dbt Fusion.

### Expected Behavior

`metric.ad_reporting.active_ads` should depend on `semantic_model.ad_reporting.ad_report` (same package namespace), matching Fusion.

### Steps To Reproduce

1. In a package (e.g. `ad_reporting`), define a model using the in-model spec ([[1](https://docs.getdbt.com/reference/model-properties?version=2)], [[2](https://docs.getdbt.com/reference/metric-properties?version=2)]), e.g.:

```yaml
  models:
    - name: ad_reporting__ad_report
      semantic_model:
        enabled: true
        name: ad_report
      agg_time_dimension: date_day
      columns:
        - name: date_day
          granularity: day
          dimension: {type: time}
        - name: ad_id
          entity: {type: primary, name: ad}
        - name: spend
          dimension: {type: categorical}
      metrics:
        - name: active_ads
          type: simple
          agg: count_distinct
          expr: ad_id
          filter: "{{ Dimension('ad__spend') }} > 0"
```
2. Install the package in a root project (add a `metricflow_time_spine`).
3. On dbt Core 1.12.3, run: `dbt --no-partial-parse ls --resource-type semantic_model`  (or `dbt compile`).

### Relevant log output

```shell

```

### Environment

```markdown
- dbt: Core 1.12.3 (works on dbt Fusion)
```

### Which database adapter are you using with dbt?

_No response_

### Additional Context

- Persists under --no-partial-parse and after dbt clean, so it is not the partial-parse bug #8859.
- Confirmed no name collisions between root project and package.
- Real-world repro: fivetran/dbt_ad_reporting#186.