Safely handle token usage, add DB save resiliency, and update dev deps

[Abdulmuiz44]

Motivation

• Prevent crashes and integer overflow when generationResult.usage.totalTokens is missing or malformed and ensure billing only charges available credits.
• Avoid hard failures when chat save/update to Supabase fails so generated responses still return usable feedback to users.
• Keep dev dependencies and lockfile in sync by adding a missing dev dependency used by the toolchain.

Description

• Parse and sanitize token usage by computing rawTokenCost = Number(generationResult.usage.totalTokens ?? 0), rounding, bounding to [1, 2_147_483_647], and deriving creditsToCharge as Math.max(1, Math.min(tokenCost, creditsRemaining)).
• Replace previous pre-check that returned an error when the token cost exceeded remaining credits with charging up to the remaining credits and continuing generation.
• Add resilient Supabase handling on both update and insert paths by logging failures via console.error and returning a user-facing error message instead of throwing, preserving generated response behavior.
• Use creditsToCharge when calling incrementUserCredits so accounting only attempts to charge available credits, and keep a retry loop for accounting with a logged warning on persistent failure.
• Add baseline-browser-mapping to devDependencies in package.json and update pnpm-lock.yaml snapshots to the new versions.

Testing

• Ran a TypeScript build and static checks (pnpm -w -s tsc and linters) to validate types and compilation, which succeeded.
• Executed the existing automated test suite (pnpm -w -s test), and all tests passed.

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Codex Task