[TheGreatAxios]

Adds free-form slides to @corbits/slidedeck: absolutely placed text, shapes, images (SVG with PNG fallback), lines and groups, with gradients, shadows, rounded corners, crops and opacity. Adds slide transitions (fade, push, wipe, morph with fade fallback) and a build timeline of entrance, emphasis and exit effects (fly, fade, wipe, zoom, grow, spin, pulse, motion paths) with click, with-previous and after-previous steps and repeats.

validateDeck rejects decks PowerPoint would mis-render: unknown targets, text under 1.34px, crops that remove the whole image, shadows whose spread flips them, and steps after an endless repeat.

Stacked on #35. Closes CL-11890

Verification

• bun run format:check, lint, typecheck, test (76 pass) in this worktree.
• Preset IDs, subtypes and wipe directions checked against LibreOffice's PowerPoint import tables.
• The fixture deck test checks unique (shape, grpId) builds, matching bldP entries, and wipe filter directions.
• Not yet opened in real PowerPoint or Keynote. Unverified there: horizontal push direction, an entrance and exit on one shape (each build now gets its own grpId), and animating an element inside a group.

[linear-code]

CL-11890

[corbits-triage]

Triage: Pass

No changes needed from you. A maintainer will review this pull request.

Stacked on #35: only this pull request's own changes were checked.

Triage will approve, request review.

[corbits-triage]

Triage requests changes:

• Conventions: added code matches a code pattern
• Invented fallbacks: added code matches a code pattern

[corbits-triage]

Triage requests changes:

• Conventions: added code matches a code pattern

[corbits-triage]

Triage requests changes:

• Conventions: added code matches a code pattern

Nothing triage asked to change still fails, so this request no longer stands.