H-2711, H-2712, H-2715: Add `/goals` and `/goals/new` pages

[CiaranMn]

🌟 What is the purpose of this PR?

Adds the following pages:

1. /goals, which lists all active goal tasks (goals are research-driven flows)
2. /goals/new, which allows creating a new goal task

For now, the goals task is a special flow definition. Later on the flow definition itself will be generated by AI.

Internal designs are here

Driveby:

• H-2712: expose model plan/explanation for actions as part of progress logs (see second demo)
• H-2715: In the browser plugin history log, show where the plugin has responded to a flow's request for a web page content

🔍 What does this change?

• ...

Pre-Merge Checklist 🚀

🚢 Has this modified a publishable library?

This PR:

• [x] does not modify any publishable blocks or libraries, or modifications do not need publishing

📜 Does this require a change to the docs?

The changes in this PR:

• [x] are internal and do not require a docs change

🕸️ Does this require a change to the Turbo Graph?

The changes in this PR:

• [x] do not affect the execution graph
• [x] affected the execution graph, and the turbo.json's have been updated to reflect this
• [x] I am unsure / need advice

⚠️ Known issues

• H-2722: The goals should have distinguishing names based on the research prompt somehow

🛡 What tests cover this?

• None yet

❓ How to test this?

1. Check out the new pages

📹 Demo

New pages

https://github.com/hashintel/hash/assets/37743469/556529d3-a16e-4228-b751-0ffd574fb1c3

Progress log tooltips with model plan / explanation of actions

https://github.com/hashintel/hash/assets/37743469/90868ff1-ef9f-4d9b-924c-d38a8f7ca0ef