Honor Markdown pipe-table column alignment in ConsoleTableRenderer

[Copilot]

Markdig's pipe-table extension records per-column alignment in Table.ColumnDefinitions[i].Alignment, but ConsoleRendererBase.TableFrame was constructing Spectre.Console TableColumns without it, so every column rendered left-aligned regardless of :---, :---:, or ---: in the source.

Changes

• ObjectRenderers/Frames/ConsoleRendererBase.TableFrame.cs: In the column-creation branch of AddRow, map TableColumnAlign to Justify and assign it to the new TableColumn. A bounds check covers the case where ColumnDefinitions is shorter than the widest row.
• Tests: Added RendererTests_TableColumnAlignment_HonorsMarkdownAlignment and ..._DefaultsToLeftWhenUnspecified that inspect renderer.Root's inner Spectre Table.Columns[i].Alignment directly (the existing TextValidation debug-mode output cannot show alignment because each cell is rendered as a nested Table, which Spectre always positions at the left of its parent cell). Also added a tableAlignment.md/.txt resource pair for regression coverage.
• docs/CHANGELOG.md: Entry under Upcoming Changes.

column.Alignment = MDTable.ColumnDefinitions[i].Alignment switch
{
    TableColumnAlign.Center => Justify.Center,
    TableColumnAlign.Right  => Justify.Right,
    _                       => Justify.Left,
};

[boxofyellow]

@copilot are you sure it is working?

[Copilot]

@copilot are you sure it is working?

Good catch — the original commit set TableColumn.Alignment but the visible cell content stayed left-flush because each cell is rendered as a nested Spectre Table (from the cell frame) and Spectre.Console doesn't apply parent column Justify to nested Table renderables. Fixed in fa4ee43 by also expanding the inner cell-frame table and aligning its single column. See the reply on the tableAlignment.txt thread for the before/after output.

[codecov]

Codecov Report

❌ Patch coverage is 94.73684% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 95.80%. Comparing base (20f15e5) to head (5f47530).

Files with missing lines	Patch %	Lines
...Renderers/Frames/ConsoleRendererBase.TableFrame.cs	94.73%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #143      +/-   ##
==========================================
- Coverage   95.82%   95.80%   -0.02%     
==========================================
  Files          30       30              
  Lines        1676     1694      +18     
  Branches      176      179       +3     
==========================================
+ Hits         1606     1623      +17     
  Misses         46       46              
- Partials       24       25       +1     

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