docs(java): clarify Sonar, Java version, and code-style guidance

[anchildress1]

• Clarify SonarQube/SonarCloud setup, token handling, and CI scanner steps
• Add guidance for Records, pattern matching, and var usage heuristics
• Provide fallbacks when static analysis is unavailable and troubleshooting steps
• Original rules are no longer included in the standard Sonar Way ruleset
• Remove future dependency on Sonar by prompting to use when integrated or available
• If not, the agent will now read Sonar rules as part of its analysis
• Removed obsolete and redundant sections on Java version and code style

Generated-by: GitHub Copilot [email protected]

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Pull Request Checklist

• I have read and followed the CONTRIBUTING.md guidelines.
• My contribution adds a new instruction, prompt, or chat mode file in the correct directory.
• The file follows the required naming convention.
• The content is clearly structured and follows the example format.
• I have tested my instructions, prompt, or chat mode with GitHub Copilot.
• I have run node update-readme.js and verified that README.md is up to date.

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Description

Fix for #296 — only I decoupled that instruction entirely from Sonar, while keeping the spirit of the rules after omitting recent deprecations and unrelated SQL-style rules from the list.

Before — Copilot would encourage user to set up Sonar connections using available tools if none was found. If user declined, no obvious path forward for Copilot.

Current — Each question provides explicit true/false path logic. If a Sonar connection already exists or if the user agrees to configure a new one, then Copilot should prefer results queried directly via tool access. If neither is true, then the same list (minus deprecated rules or ones explicitly removed from Sonar's recommended list for Java) serves as a semantic reference for Copilot to work from.

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Type of Contribution

• New instruction file.
• New prompt file.
• New chat mode file.
• Other (please specify): instruction update to resolve SonarSource rule IDs and descriptions in java.instructions.md don't correlate #296 by eliminating explicit sonar dependency in favor of local extension or MCP.

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Additional Notes

🦄 This option really isn't as strong as it would be if the tool was available, but it also prevents broken logical path structures; and ambiguous instructions if no clear path forward exists.

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By submitting this pull request, I confirm that my contribution abides by the Code of Conduct and will be licensed under the MIT License.

[Copilot]

Pull Request Overview

This PR updates Java instructions to decouple static analysis guidance from SonarQube dependency while maintaining code quality standards. It provides clearer setup guidance and fallback options when static analysis tools are unavailable.

Key changes:

• Enhanced SonarQube/SonarCloud setup instructions with specific CI configuration steps
• Converted rule-based tables to human-readable guidelines that work with any static analysis tool
• Added fallback mechanisms and troubleshooting steps when Sonar is unavailable