DAG Overview "Last N Dag Runs" duration chart tooltip shows wrong (first-run) data when hovering later runs

### Under which category would you file this issue?

Airflow Core

### Apache Airflow version

3.0.6

### What happened and how to reproduce it?

**Issue Description**

On the DAG's Overview page, the "Last N Dag Runs" duration bar chart (the
component appears to be `DurationChart` in `Overview.tsx`) shows an incorrect
tooltip when hovering over different bars. For a DAG scheduled multiple times
per day, hovering over the second (or any later) run's bar still shows the
timestamp/duration belonging to the *first* run in the chart, instead of the
data for the bar actually being hovered.

This is a data-accuracy bug in the tooltip, not a rendering/visibility issue
like the "tooltip never goes away" problem reported in #56250 (item 17) —
here the tooltip does appear/disappear correctly, but the content is bound to
the wrong data point.

**Steps to reproduce:**
1. Have a DAG scheduled more than once per day (e.g. `schedule='30 8,20 * * 1-5'`)
with several days of successful run history.
2. Open the DAG's Overview page.
3. In the "Last N Dag Runs" duration chart, hover the mouse over the bar for
the first run of a given day, note the tooltip's time.
4. Hover over the bar for the second run of the same day.
5. Observe: the tooltip still shows the same time as step 3, instead
of updating to the second run's own data.

### What you think should happen instead?

Each bar's tooltip should reflect that specific dag_run's own start
time/duration, not the first bar's data. This makes the chart actively
misleading when trying to compare run durations across a day with multiple
scheduled runs — the exact use case the chart is meant to support.

### Operating System

Rocky Linux 9 (SELinux Enforcing)

### Deployment

Virtualenv installation

### Apache Airflow Provider(s)

_No response_

### Versions of Apache Airflow Providers

apache-airflow-providers-standard, apache-airflow-providers-fab, apache-airflow-providers-celery, apache-airflow-providers-postgres, apache-airflow-providers-redis

### Official Helm Chart version

Not Applicable

### Kubernetes Version

Not Applicable

### Helm Chart configuration

Not Applicable

### Docker Image customizations

Not Applicable

### Anything else?

Deployment is a bare-metal (non-Docker) install via conda env + systemd,
CeleryExecutor, PostgreSQL metadata DB, Redis broker. Issue is 100%
reproducible, every time, on any multi-run-per-day DAG — not intermittent.

This seems related to the same DurationChart component discussed in #56250
(a collection of AF3 UI issues), which already lists a different tooltip bug
on this same chart ("tooltip that never goes away hides the latest bars").
That suggests this chart component has had several distinct, unresolved
issues across the 3.x line.

### Are you willing to submit PR?

- [ ] Yes I am willing to submit a PR!

### Code of Conduct

- [x] I agree to follow this project's [Code of Conduct](https://github.com/apache/airflow/blob/main/CODE_OF_CONDUCT.md)

Start in the DurationChart component referenced in Overview.tsx and reproduce the issue with a DAG scheduled multiple times per day. Verify that hovering each bar uses that dag_run's own start time and duration, rather than the first run's data.

Written by the indexing model from the issue text.