feat(usage): add api_kind field to microdollar_usage_metadata

[kilo-code-bot]

Summary

Adds an api_kind field (e.g. chat_completions, responses, fim_completions, embeddings, messages) to microdollar_usage_metadata, using the same normalized lookup-table pattern as editor_name.

• New api_kind lookup table with a unique index and serial PK
• New api_kind_id FK column on microdollar_usage_metadata
• microdollar_usage_view extended with api_kind via a LEFT JOIN
• UsageMetaData type updated with api_kind: string | null
• extractUsageContextInfo now forwards api_kind from MicrodollarUsageContext (already present there)
• insertUsageAndMetadataWithBalanceUpdate CTE extended with createUpsertCTE for api_kind
• Benchmark script and admin dev-insert route updated to satisfy the updated type
• No migration included — will be auto-generated

Verification

• pnpm typecheck passes (all packages)
• pnpm format:check passes

Visual Changes

N/A

Reviewer Notes

api_kind was already present on MicrodollarUsageContext (used for branching logic) but was never persisted to the database. This PR closes that gap using the established normalized storage pattern.

[kilo-code-bot]

Code Review Summary

Status: No Issues Found | Recommendation: Merge

Files Reviewed (9 files)

• packages/db/src/migrations/0051_chemical_ultimatum.sql
• packages/db/src/migrations/meta/0051_snapshot.json
• packages/db/src/migrations/meta/_journal.json
• packages/db/src/schema.ts
• src/app/admin/api/users/[id]/dev/insert-usage-record/route.ts
• src/lib/processUsage.ts
• src/lib/processUsage.types.ts
• src/scripts/usage/benchmark-insert-usage.ts
• src/tests/helpers/microdollar-usage.helper.ts

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_{Reviewed by gpt-5.4-20260305 · 2,154,116 tokens}

[jrf0110]

If this is a known enum, we can express it via typescript:

Suggested change

	api_kind: text().notNull(),
	api_kind: text().$type<'chat_completions' | 'responses' | 'fim_completions' | 'embeddings' | 'messages'>().notNull(),

[chrarnoldus]

alright, I'll do it in a follow-up because I'll probably need to move the type