fix: arrange the tree on every render pass, not only on a resize

[matt-edmondson]

Fixes #133

What was wrong

UIApplication.SyncRootToConsole ran ArrangeTree only when the root had no size yet or the terminal had been resized. After the first frame, any other change to the tree kept its old layout:

• an element shown with IsVisible = true kept its empty size and was never drawn
• a root the host sized itself skipped arrange completely, so its children were never drawn
• text that changed length didn't move its siblings

Change

• The rules for adopting the terminal size are unchanged. The terminal size still applies when the root has no size or the terminal is resized, and a size the host assigns is still kept between resizes.
• ArrangeTree(root) now runs on every pass. Each pass already clears and redraws the whole screen, so an extra arrange costs little by comparison.
• The CLAUDE.md note on the rendering flow is updated to match.

Tests

• UIApplicationLayoutTests adds three tests: the two reproductions from the issue, and one where text grows and moves its sibling.
• With the fix reverted, all three fail. With the fix in place, all three pass.
• The full TUI.Test suite passes, 224 tests, including the existing resize tests and RenderWithoutAResizeLeavesAHostAssignedRootSizeAlone.

🤖 Generated with Claude Code

https://claude.ai/code/session_01F4JLDZ8V6BpUZBB9ZnsaNt

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Generated by Claude Code

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

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