Debug helpers: clear stuck dialogue and re-enable controls

[GhostWriter42]

Draft: not compiled or tested yet. I've only reviewed this statically. I haven't built it or run it in a 2-client co-op session. The planned check is below, and I'll update this PR once I've done it.

What

• New F3 Helpers → "Clear stuck dialogue" button: calls StopCurrentDialogue(true) on the player, then unblocks and re-enables PlayerControls. No knockback.
• "Unstuck player" now does the same clear first, then the existing knockback, and null-checks currentProcess.

Why

In co-op, guests sometimes get stuck in a dialogue or scene with input blocked, for example when the scene's NPC packages run on the leader's client. "Unstuck player" only applied a knockback, which doesn't release a stuck dialogue or blocked controls. This gives players a manual way out without touching quest stages, scene state, or networking.

How tested

Not tested yet: no compile and no 2-client run so far.

Planned 2-client check: reproduce a guest dialogue hang. "Clear stuck dialogue" should give control back without moving the player, and "Unstuck player" should give control back and then knock the player.

Related

• Several dialog & subtitle improvements in the way Scenes / Cutscenes work in a party #854 (dialog & subtitle improvements for scenes / cutscenes) goes after the root causes. This is only a manual fallback, and it doesn't conflict with Several dialog & subtitle improvements in the way Scenes / Cutscenes work in a party #854 at the file level (it only changes DebugService.cpp).