[aaltshuler]

Graph imports now provide bounded preparation, cancellation, and progress reporting. The demo previews CSV data before import, supports explicit column mapping and an optional nodes file, and preserves the current graph when an import fails or is cancelled.

This also adds live overview subscriptions and a shared position cache for labels and the minimap, opt-in columnar output across all five import formats, and a runnable first-graph quickstart checked against packed packages. Object output remains the default, and the v1 artifact format is preserved. A changeset prepares the next coordinated minor release.

Validation:

• Workspace checks, package tests and builds, demo and Storybook builds, and packed-package consumer checks pass.
• All 55 headed browser tests pass, including real-GPU interaction, live OmniGraph 0.14, guided imports, and minimap updates.
• Columnar retained prepared-result memory falls from 70.2 to 18.5 MiB in the checked-in benchmark; preparation is slower and peak RSS does not improve.
• Large-graph frame p95 is 42.11 ms versus 41.81 ms baseline, with zero idle callbacks in all three final runs. Both exceed the existing 33 ms budget; this change does not claim to resolve that pre-existing limit.