Add in-memory storage mode (default) and storage option; update README

[QuenumGerald]

Motivation

• Make the scheduler run in RAM by default to simplify local usage and avoid implicit file persistence.
• Provide an explicit storage option to allow choosing between in-memory and SQLite-backed persistence.
• Document the default behavior and how to enable SQLite persistence in the README (French additions).

Description

• Add storage?: 'sqlite' | 'memory' to BlazeJobOptions and make dbPath optional, and derive dbPath from storage with :memory: used for memory mode.
• Initialize SQLite database path inside the constructor using const useMemoryStorage = options.storage !== 'sqlite' and call new Database(dbPath) accordingly.
• Change server bootstrap in startServer to create jobs = new BlazeJob({ storage: 'memory' }) by default and reuse the scheduler's DB instance via db = jobs['db'] instead of creating a separate Database('blazerjob.db') instance.
• Preserve existing table creation and schema migration logic; keep encryption key helper behavior and encryption/decryption helpers intact while making dbPath optional.
• Update README.md with examples showing the default RAM mode and how to enable SQLite persistence, with code snippets in TypeScript and French explanatory text.

Testing

• Built the TypeScript project with tsc and the build completed successfully.
• Ran the test suite with npm test and all automated tests passed.
• Ran linting with npm run lint and it reported no issues.

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[chatgpt-codex-connector]

Keep dbPath-only callers on SQLite storage

The new default const useMemoryStorage = options.storage !== 'sqlite' makes existing new BlazeJob({ dbPath: ... }) callers silently switch to :memory: because storage is usually omitted. In this repo, src/bin/cli.ts still uses dbPath-only construction for schedule, list, and delete, so tasks written by one CLI invocation are no longer visible to the next process, breaking persistence semantics. This is a behavioral regression for existing integrations and should be fixed by inferring SQLite when dbPath is provided unless storage: 'memory' is explicitly set.

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