fix(docs): update stale "Future (~Fall 2025)" column header in migration guide

[Kewe63]

Summary

Closes #1315

The migration guide table header at docs/base-account/guides/migration-guide.mdx:18 referenced "Future (~Fall 2025)" which has already passed (we are now in mid-2026). The header was misleading readers about the migration timeline.

Updated the column header from Future (~Fall 2025) to Current to reflect the actual present-day state of the migration.

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Diff

Before	After
| User Type | Today | Future (~Fall 2025) |	| User Type | Today | Current |

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Verification

• Read docs/base-account/guides/migration-guide.mdx in full to ensure the change is self-contained (only the header row was touched).
• The "Today" / "Current" semantics now match: both columns describe the current state, as the originally future-projected Fall 2025 deadline has passed.

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Checklist

• Documentation-only change (no code, no config, no images)
• Verified no other references to "Fall 2025" in the same file
• git diff --stat shows 1 file, +1/-1

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Risk & Impact

None. Single-line documentation header fix. No code, config, or behavior changes.

Type: 📝 Documentation
Closes: #1315

[cb-heimdall]

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