Robust token accounting and persistence warnings; add baseline-browser-mapping devDependency

[Abdulmuiz44]

Motivation

• Ensure token usage and charging are robust against malformed or large values and avoid failing generation when user credits are low.
• Prevent hard failures on DB write issues so responses can still be returned while surfacing persistence warnings.
• Keep dependency graph consistent by adding a missing dev dependency needed in lockfile updates.

Description

• Replace previous token cost logic with safe parsing and clamping: compute rawTokenCost, round and clamp to [1, 2_147_483_647], and derive creditsToCharge as Math.max(1, Math.min(tokenCost, creditsRemaining)).
• Remove early error return when tokenCost > creditsRemaining so responses are still generated and allow charging up to remaining credits.
• Replace thrown errors on Supabase update/insert failures with console.error logs and set a persistenceWarning string so the API returns the generated answer with a warning instead of failing.
• Use creditsToCharge when calling incrementUserCredits, keep retry logic, and consolidate persistenceWarning and usageAccountingWarning into a single warning returned to callers.
• Add baseline-browser-mapping to devDependencies in package.json and update the pnpm-lock.yaml snapshots to match the upgraded dependency versions.

Testing

• Ran TypeScript checks with tsc --noEmit and the code type-checks successfully.
• Executed the test suite with pnpm test and all tests passed.
• Performed a local build with pnpm build to validate install and lockfile changes, and the build completed successfully.

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Codex Task