Summary

Change the default alignment for @block from center to centerLeft.

Motivation

• Most presentation content is paragraph-like text (multi-line, left-to-right reading), so centerLeft matches the most common scenario.
• Left-aligned body text is typically easier to scan/read, especially for multi-line paragraphs.
• center feels better suited for titles or short callouts; for general content blocks, centerLeft is a more ergonomic default.

Proposed Solution

• Update the @block default align to centerLeft.
• Keep align: center available as an explicit option.

Acceptance Criteria

• A @block with no explicit align renders as centerLeft.
• Existing decks can restore the old behavior by setting align: center.
• Docs/reference mention the default alignment change.

Alternatives Considered

• Keep default as center (status quo), but this requires most text-heavy decks to override alignment frequently.

Additional Context

If this is considered a breaking change, it could be gated behind a versioned option (e.g. deck-level default or a compatibility flag).