Handle DB failures and tighten token accounting; add baseline-browser-mapping devDependency

[Abdulmuiz44]

Motivation

• Prevent failures during chat save or credit accounting from crashing response generation and provide clear warnings to the client.
• Make token usage parsing robust against malformed/huge values and ensure safe integer bounds when charging credits.
• Add a missing dev dependency to keep lockfile consistent.

Description

• Replace fragile token cost calculation with rawTokenCost = Number(generationResult.usage.totalTokens ?? 0) then sanitize using Number.isFinite, Math.round, and clamp to 1..2_147_483_647, and compute creditsToCharge as Math.max(1, Math.min(tokenCost, creditsRemaining)).
• Stop throwing on Supabase insert/update errors and instead log errors with console.error, set a persistenceWarning, and track chatPersisted so generation still returns an answer even if DB persistence fails.
• Use creditsToCharge when calling incrementUserCredits and retry accounting up to maxAccountingAttempts, emitting a usageAccountingWarning and logging if accounting fails.
• Consolidate persistenceWarning and usageAccountingWarning into a single warning field and compute sessionId returned as currentSessionId only when the chat was actually persisted.
• Add baseline-browser-mapping to devDependencies in package.json and update pnpm-lock.yaml accordingly.

Testing

• No automated tests were run for this change.

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Codex Task

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Surface chat persistence failures through existing error path

When the chat update/insert fails here, the function now logs and sets persistenceWarning instead of returning an error, then still returns a successful payload. The only caller (components/PromptShell.tsx, where the result is destructured into answer, sessionId, chatId, and error) does not read warning, so in this failure mode the UI treats the response as saved even though nothing was persisted. This creates silent data loss on refresh whenever Supabase writes fail.

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