fix: correct function usage period totals

[HarshMN2345]

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Greptile Summary

• Migrates the function usage page from Svelte 4 reactive declarations (export let data, $:) to Svelte 5 ($props(), $derived), and replaces the API-provided executionsTotal with a sum computed from the period's metric series so that the displayed total reflects the selected time window rather than a lifetime value.
• Adds isCumulative to both Usage chart components, switching from the accumulateFromEndingTotal chart projection to plotting per-period values directly, consistent with the new sum-based totals.
• The previously flagged P1 (always-truthy {#if count} array guard) is addressed in this PR by changing to {#if count.length}.

Confidence Score: 4/5

Safe to merge; no P0 issues found and the previously reported P1 (always-truthy array guard) has been resolved.

The only open concern is the rename from data.executionsMbSeconds to data.executionsTime — if the SDK type does not expose executionsTime, the GB-hours card would silently never render. However, since the page uses typed PageProps, TypeScript would catch a missing field at build time, so the risk is low. All other logic is correct.

No files require special attention beyond verifying the executionsTime field exists in the SDK type for functions.getUsage().

Important Files Changed

Filename

Overview

src/routes/(console)/project-[region]-[project]/functions/function-[function]/usage/[[period]]/+page.svelte

Migrates from Svelte 4 reactive declarations to Svelte 5 $derived, fixes period-total computation by summing series values instead of using the server-provided executionsTotal, adds isCumulative to both Usage cards, and renames executionsMbSeconds to executionsTime. One previously flagged P1 (always-truthy {#if count} guard) is resolved; gbHoursTotal is computed from the filtered gbHoursCount array, which is mathematically correct since filtered-out zeros do not affect the sum.

_{Reviews (2): Last reviewed commit: "refactor: improve periodic usage charts" | Re-trigger Greptile}