Fix negative values breaking server launch in --reconnection-grace-time

[Copilot]

Setting --reconnection-grace-time to a negative value (e.g., -1000) causes the CLI parser to fail with "unexpected argument '-1' found".

Changes

CLI argument parsing

• Changed reconnection_grace_time type from Option<u32> to Option<i32> in cli/src/commands/args.rs and cli/src/tunnels/code_server.rs
• Allows the CLI to parse negative values without error
• Existing TypeScript validation in parseGraceTime() already handles negative values by falling back to defaults

Tests

• Added unit tests in src/vs/server/test/node/serverEnvironmentService.test.ts covering negative, zero, empty, and invalid value handling

The unsigned integer constraint at the CLI layer was premature - validation properly occurs in TypeScript where negative values are rejected with logging.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Negative values break server launch</issue_title>
<issue_description>Testing #280450

• Set reconnectionGraceTime to -1000
• Restart the server

[20:05:54.210] > error: unexpected argument '-1' found

</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Negative values break server launch #280559

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