[rohithreddykota]

Adds a "Backfill range" view to the model partitions dialog, so incremental models can refresh a contiguous range of partitions from the UI after previewing exactly which partitions will run.

• Pick a partition data field, enter an inclusive start and end, and preview the matched partitions before confirming; confirming sends their keys through the existing RefreshModelTrigger.partitions.
• Numeric values compare numerically (including numeric strings); everything else compares as strings, which orders ISO dates correctly. An end like 2026-03-08 also includes 2026-03-08T00:00:00Z.
• Shows read-only execution settings before submitting: partition concurrency and retry settings (attempts, delay, backoff, matched error patterns), with runtime defaults when retry is unset.
• Adds ModelState.partitions_concurrency, set by the model reconciler to the concurrency the executor actually resolved (partitions_concurrency combined with connector limits) and cleared for non-partitioned runs. The UI prefers the configured partitions_concurrency, then this observed value.
• Warns when other pending partitions will run with the backfill, disables submit while the model is reconciling, and polls the partitions list after triggering.
• The dialog is shared, so this works in both Rill Developer and Rill Cloud. Only shown for incremental models.

Tested with npx vitest run src/features/models/partitions/partition-range.spec.ts (16 tests passing), go test ./runtime/reconcilers/..., golangci-lint run ./runtime/reconcilers/..., and npm run quality across web-common, web-local, and web-admin.

Checklist:

• Covered by tests
• Ran it and it works as intended
• Reviewed the diff before requesting a review
• Checked for unhandled edge cases
• Linked the issues it closes
• Checked if the docs need to be updated. If so, create a separate Linear DOCS issue
• Intend to cherry-pick into the release branch
• I'm proud of this work!