feat: promote DataIngesting status to first-class citizen in SDK

[maurocolella]

Add DataIngesting as a first-class execution status

DPS synthesizes a transient DataIngesting status while result data is being ingested after tool execution completes. This PR teaches the SDK about it:

• Added to PlatformStatus Literal, transition map, and non-terminal/non-failed sets
• Badge renders as light-blue (info) with an animated "Ingesting data…" progress bar
• cancel() now permitted during DataIngesting
• wait() and watch_async() automatically poll through it (non-terminal)
• DPS mock simulates the status via metadata.__data_ingestion_started
• 7 new tests covering polling, cancellation, display, and terminal checks
• Docs updated

[sg-s]

mauro -- i think there's someting lost in translation -- the client's execution lifecycle (get / sync / wait / watch) polls tools-service (Mason), not data-platform. DataIngesting is synthesized only on the DPS executions projection when deferring terminal upserts during result ingestion- mason never emits it. s oadding DataIngesting to PlatformStatus, terminal sets, and wait/watch behavior is effectively unreachable from current client paths unless we also switch status polling to DPS (or a unified API). imo this looks like dead code relative to how clients actually observe execution state