Emoji table column misalignment regression (v1.0.43) — #2764 not fully fixed

## Description

#2764 was closed as fixed in v1.0.32, but emoji column misalignment persists in v1.0.43. Emoji characters in table cells cause column borders to shift and extra `|` pipe characters render inside cells.

## Steps to Reproduce

Prompt:
```
echo this table back to me | Test | Rate | Status | Fix |
|------|------|--------|-----|
| FooTest | 12/12 | ❌ Unresolved | #123 didn't fix |
| BarTest | 7/12 | 🔧 Merged | #456 May 8 |
| BazTest | 6/12 | 🔶 Partial | #789: 100%→25% |
| QuxTest | 4/12 | ❓ No fix | — |
| QuuxTest | 3/12 | ✅ Ready | PR #101 |
| CorgeTest | 2/12 | 🟡 Flaky | — |
```

## Expected

Columns align correctly. Emoji counted as correct display width.

## Actual

- Status column with emoji shifts subsequent column borders right
- Extra `|` pipe characters appear inside rendered cells
- Column widths inconsistent between rows with different emoji

## Environment

- Copilot CLI version: 1.0.43
- OS: macOS
- Terminal: IntelliJ built-in terminal
- Shell: zsh

## Ref

- #2764 — originally reported, closed as fixed in v1.0.32
- Fix claim: "Tables render with correct column widths, emoji support, and stable borders during terminal resize"

Reproduce the supplied table prompt in Copilot CLI 1.0.43 on the stated terminal, then trace the table-rendering and display-width handling entry points. Compare rows containing emoji with plain-text rows and verify that columns align, no extra pipe characters appear, and widths remain consistent.

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