Feat: Edit Timer `start` or `stop` time to adjust duration

In the first instance our app needs to be useful for the _individual_ using it. i.e. ["single player mode"](https://github.com/dwyl/product-roadmap/tree/c3493258d0355ba2cb04d4ed61052483f49d5f8b#3-stages-of-our-roadmap).

# Story

As a **`person` tracking time spent** on **`items`** on my task list, ✅
**I want** the ability to ***`edit`*** the **`timer.start`** or **`timer.stop`** value 📝
**So that** my timers accurately reflect the _actual_ time spent on a task.👌

## Reasoning

I might **forget** to **`start`** the timer, so I didn't time the task at all.
***or*** neglect to **`stop`** a timer a so it ends up clocking up _way_ more time than it actually took,
both of these scenarios are undesirable and might put the person off _using_ the App/Tool.

## Analysis

From the perspective of the **backend/API** this is a ***trivial*** feature to implement
as it's just updating the value in a row/record i.e. **`T25m`** with tests and docs.
But from the perspective of the front-end/UX it's a _lot_ more nuanced.

### UX/UI?

Will the input be a numeric field where the person can manually input date and time values.
Or will it be a _picker_ that facilitates input? in which case what is the desired UI/UX?

e.g. would we have a date picker: https://flowbite.com/docs/plugins/datepicker/

Coupled with a **`timepicker`**: https://tailwind-elements.com/docs/standard/forms/timepicker/

## Open Questions

Do we want _all_ timers to be editable? 💭
How far back should people be able to edit their timer? e.g. should we _limit_ it to recent?
Should we record the **_original_ `start`** and **`stop`** for audit trail purposes?