feat: add Scala general cursorrules and with Kafka usage, closes #83

[seyfer]

This is a proposal for general Scala cursor rules with Kafka usage.
These have already been tested for a few months at my main workplace.

Summary by CodeRabbit

• Documentation

  • Added a comprehensive Scala 3 development best practices guide, including coding standards for Kafka Streams projects.
  • Introduced clean code guidelines for Scala, covering variable naming, immutability, and code complexity.
  • Added linting and formatting rules enforcing a Google-inspired scalafmt configuration with a 100-column line length.
  • Added Kafka development best practices for Scala projects, including topic configuration, serialization, and testing guidelines.

• Chores

  • Added a .gitignore entry to exclude the .idea directory from version control.

[coderabbitai]

"""

Walkthrough

This update introduces a .gitignore file to exclude JetBrains IDE settings and adds four new markdown rule files defining comprehensive Scala coding standards, clean code guidelines, Kafka development best practices, and linting/formatting rules for a Kafka Streams project.

Changes

File(s)	Change Summary
.gitignore	Added to ignore .idea directory (JetBrains IDE settings).
rules/scala-kafka-cursorrules-prompt-file/general-scala-clean-code.mdc	New rules file with Scala clean code guidelines (variable scope, naming, for-comprehension depth, immutability).
rules/scala-kafka-cursorrules-prompt-file/general-scala-development-practices.mdc	New detailed Scala 3 coding standards and best practices for Kafka Streams projects.
rules/scala-kafka-cursorrules-prompt-file/linting-formatting.mdc	New linting/formatting rule enforcing Google-inspired scalafmt with 100-column line limit.
rules/scala-kafka-cursorrules-prompt-file/kafka-development-practices.mdc	New Kafka-specific development best practices for Scala projects (topic config, serialization, testing).

Estimated code review effort

2 (~20 minutes)

Poem

In the warren where Scala streams flow,
New rules and clean code now brightly glow.
With .idea ignored, and scalafmt in line,
Kafka hops smoothly—oh, how divine!
🐇✨ Let’s write with care, and code with glee,
For in tidy burrows, the best bugs flee!
"""

---

📜 Recent review details

Configuration used: CodeRabbit UI
Review profile: CHILL
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📥 Commits

Reviewing files that changed from the base of the PR and between 9588bfe and 29dc1d5.

📒 Files selected for processing (3)

• rules/scala-kafka-cursorrules-prompt-file/general-scala-clean-code.mdc (1 hunks)
• rules/scala-kafka-cursorrules-prompt-file/general-scala-development-practices.mdc (1 hunks)
• rules/scala-kafka-cursorrules-prompt-file/kafka-development-practices.mdc (1 hunks)

✅ Files skipped from review due to trivial changes (1)

• rules/scala-kafka-cursorrules-prompt-file/kafka-development-practices.mdc

🚧 Files skipped from review as they are similar to previous changes (2)

• rules/scala-kafka-cursorrules-prompt-file/general-scala-clean-code.mdc
• rules/scala-kafka-cursorrules-prompt-file/general-scala-development-practices.mdc

---

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[coderabbitai]

Actionable comments posted: 3

🧹 Nitpick comments (1)

.gitignore (1)

1-2: Add common Scala / sbt artefacts to .gitignore.

Only ignoring .idea will still leave generated build artefacts and Metals/BSP files under version control. At minimum add:

 .idea
+target/
+.bsp/
+.metals/
+.project
+.classpath

This keeps the VCS clean for anyone using the usual Scala tooling.

📜 Review details

Configuration used: CodeRabbit UI
Review profile: CHILL
Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between 42ac7cf and 61c698b.

📒 Files selected for processing (4)

• .gitignore (1 hunks)
• rules/scala-kafka-cursorrules-prompt-file/general-scala-clean-code.mdc (1 hunks)
• rules/scala-kafka-cursorrules-prompt-file/general-scala-development-practices.mdc (1 hunks)
• rules/scala-kafka-cursorrules-prompt-file/linting-formatting.mdc (1 hunks)

[seyfer]

to be reviewed by @PatrickJS