Follow-up to issue #3092, replacing its superseded scope after identifying that both hover-only actions can cause the same layout shift.

Justification and motivation

The workspace and pin actions currently appear on hover in the wrapping title row. When a title already fills the available width, revealing either action can push the actions onto another line and increase the issue row height. This produces a jarring layout shift while scanning the issues list.

Moving both actions into the existing fields/label row gives them a predictable location. Reserving their space keeps fields and row height stable when hover reveals them, while retaining hover-only visibility keeps visual noise low.

What we want done

• In the issues list only, move both the workspace action (W) and pin action (P) from the title row to the fields/label row.
• Place both actions immediately after State when State is visible.
• When State is hidden through Fields & Links, place both actions at the start of the fields row.
• Keep both actions hover-only, but always reserve space for them so revealing them moves neither fields nor row height.
• Leave pull request list behavior unchanged.

Before

Without hover, neither action is visible:

┌──────────────────────────────────────────────────────────┐
│ #3092  A long issue title that fills the title row       │
│ [Open]  [Normal]  [Assignee: servicedesk]                │
└──────────────────────────────────────────────────────────┘

With hover, both actions are inserted after the title. When the title fills the row, they wrap and make the issue row taller:

┌──────────────────────────────────────────────────────────┐
│ #3092  A long issue title that fills the title row       │
│ [W] [P]                                                  │
│ [Open]  [Normal]  [Assignee: servicedesk]                │
└──────────────────────────────────────────────────────────┘

After

Without hover, space for both actions is reserved immediately after State:

┌──────────────────────────────────────────────────────────┐
│ #3092  A long issue title that fills the title row       │
│ [Open]  ··· ···  [Normal]  [Assignee: servicedesk]       │
└──────────────────────────────────────────────────────────┘

With hover, both actions occupy their reserved slots, so neither the fields nor the row height moves:

┌──────────────────────────────────────────────────────────┐
│ #3092  A long issue title that fills the title row       │
│ [Open]  [W] [P]  [Normal]  [Assignee: servicedesk]       │
└──────────────────────────────────────────────────────────┘

If State is hidden, both reserved slots and actions move to the start of the fields row:

no hover: │ ··· ···  [Normal]  [Assignee: servicedesk]     │
hover:    │ [W] [P]  [Normal]  [Assignee: servicedesk]     │

Acceptance criteria

• Hovering an issue row never increases its height when either action appears.
• Both actions are next to State when State is visible and at the start of the fields row otherwise.
• Both actions remain hover-only, with their space reserved before hover.
• Pull request list behavior remains unchanged.

Watchers carried over from issue #3092: @robin, @zaakiy, @servicedesk.