docs(web): update LSP docs wording

[StarpTech]

Issue for this PR

Closes #

None

Type of change

• Bug fix
• New feature
• Refactor / code improvement
• Documentation

What does this PR do?

• Clarify that LSP is disabled by default and must be enabled explicitly
• Reframe LSP as optional agent-loop diagnostic feedback rather than code intelligence
• Add Best Practices guidance covering LSP tradeoffs and when diagnostic CLI tools may be preferable
• Align localized LSP docs with the English documentation

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Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR

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