feat: bring repeaters, paging, and tooltips to full-screen windows - #128

Closes #119
Part of #115

What's supported on full-screen windows

• Bound text, switches, tints, bars: already bound by feat(runtime): add the full-screen session with fake-survival input and a hidden HUD #125 and checked in a real client. This PR doesn't change them.
• Repeaters: each cell is its own canvas control, with its own hit-test, hover outline and indexed action (onX(index, click: FullscreenClick)). The industrial <Repeater> now sizes cells at 18px per slot outside sections too. Before this, cells collapsed to their content on the canvas. Container goldens are unchanged.
• Paging: FullscreenView.list(...) creates the same WindowList as WindowView.list(...). It feeds indexed renders through at(cell), and canPrevious()/canNext() back the flags on the paging buttons.
• Tooltips: <Region tooltip> and the industrial controls built on it, including Tabs labels and Button disabled={{ tooltip }}. See the decision below.

Tooltip decision

The compiler lays each tooltip out beside its control: centred below it, or above it where the canvas runs out, and always kept on the canvas. The panel is vanilla-styled (dark fill, purple border, cut corners). The title is white and the lines are grey, both plain text. The panel is baked art, and the lines are static labels. The session sends the hovered control's tooltip next to its outline, in two new layers (252 panel, 253 text) under the overlay layer. That cuts the content layer limit from 252 to 250. Panels with the same rect share one texture.

I didn't make the tooltip follow the cursor, for two reasons:

• Horse mode: text.vsh can't see the cursor there, because the entity shader draws it.
• Font rows: vanilla text can't be shifted above its line (row ≥ −1), so a tooltip under the cursor couldn't flip up at the bottom edge. Composing it at the cursor's position on the server would need a font for every canvas row.

Anchoring to the control fits the existing server-driven hover. The runs are only re-sent when the hovered control changes, and it works the same in both modes. MiniMessage tags are a build error, because the panel is sized from the plain text at compile time.

Items decision

Real items stay container-only. These fail the build and say why: <Items>, <Collection>, a <Repeater item>, and <Section>s (the message now reads "only available in container windows"). I didn't build item icon rendering.

Rejected at compile time

Checks

• just test-rust -p window-core fullscreen / layout
• just golden: only fullscreen was updated on purpose (repeater and tooltips added). Every other case is unchanged.
• just gradle :runtime:test --tests '*Fullscreen*' :minestom:test --tests '*Fullscreen*'
• just check-ts
• just lint
• The golden case's generated Kotlin compiled against the runtime in a throwaway check.

Not yet verified in a real client

• Tooltip panel and text layering and position.
• Per-cell hover and outline on repeaters.
• Paging re-renders.