Add top/bottom vertical alignment for inline boxes

[nicoburns]

LLM Contributions: This PR (code and description) was authored by Devin, directed and reviewed by @nicoburns.

Top PR of the stack (#9 → #10 → #7).

Implements vertical-align: top/bottom for inline boxes, which parley previously treated as baseline-aligned — fixing the floats-wrap-bfc-002-* WPT tests (Group C2 in DioxusLabs/blitz#627) where a strut descent was wrongly added below vertical-align: bottom inline-blocks.

• InlineBox gains vertical_align: InlineBoxVerticalAlign (Baseline (default) / Top / Bottom).
• InlineBoxAlignment gains a TopOrBottom { height } variant: such boxes grow the line box (tracked as LineBoxMetrics::top_or_bottom_box_height, with extra space added below the baseline) without moving the baseline.
• GlyphRunIter positions them flush with the line's block_min_coord/block_max_coord instead of relative to the baseline.
• Test/example changes are mechanical vertical_align field initializers.

Changelog

Added

• InlineBox::vertical_align (InlineBoxVerticalAlign::Baseline/Top/Bottom) to align an inline box with the top or bottom of the line box instead of the baseline.

Link to Devin session: https://dioxus.staging.devinenterprise.com/sessions/6ab608fbe6fb46479d6dab03fedceb25

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