Improve Marketplace discovery and standardize English language

[suzdalenko-dev]

What changed

• Renamed the Marketplace display title to Simple DB - SQL Client for SQLite, MySQL, PostgreSQL, SQL Server & Oracle.
• Added an English Marketplace/search-oriented description and 25 database/SQL discovery keywords.
• Added the dedicated 256×256 Simple DB Marketplace icon and connected it through package.json.
• Standardized the entire first-party project surface in English: README.md, CHANGELOG.md, delivery plan, product requirements, CI/launch labels, extension commands/settings, UI and error messages, generated DDL guidance, source comments, and test descriptions/fixtures.
• Updated the result view language metadata from es to en.
• Kept the database architecture, dependencies, query behavior, transaction behavior, and row-limit policy unchanged.

Why

Simple DB is intended for Marketplace users searching for Oracle, MySQL, PostgreSQL, SQL Server/MSSQL, SQLite, SQL editors, and database clients. The repository and installed extension should present one consistent English-language experience instead of mixing English Marketplace metadata with Spanish documentation and UI text.

Validation

• Repository language audit: no first-party Spanish documentation/UI matches remain
• ESLint: passed
• Vitest: 11/11 files, 50/50 tests passed
• npm audit --omit=dev: 0 vulnerabilities
• npm run package: passed
• VSIX ZIP integrity: passed
• Marketplace icon present in the packaged VSIX
• Remote Git tree SHA matches the locally tested tree SHA exactly: 767032171cccfebcd9824cfd9a352d771bede756