feat(editor): add spotlight area annotations

[wardmos]

Summary

• add rectangle, rounded rectangle, and ellipse annotation shapes with an independently toggled Spotlight style
• preserve original pixels inside one or more focus regions while dimming the surrounding screenshot
• keep shape selection separate from Spotlight and annotation color controls
• support selection, movement, deletion, undo/redo, export, localization, distinct icons, and documentation

Checks

• pytest -q (1552 passed, 4 skipped)
• ruff check src tests
• ruff format --check src tests
• git diff --check origin/main...HEAD

Notes

• Source changes intentionally trigger CI and package smoke workflows.