chore: import upstream snapshot with attribution

.github/instructions/code-review.instructions.md

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+---
+applyTo: "**"
+excludeAgent: ["coding-agent"]
+---
+
+# Code Review Instructions
+
+## Knowledge Cutoff
+
+Your training data has a cutoff. Treat anything you don't recognize as **new, not wrong**. Here are things you might flag as incorrect but are actually valid:
+
+- Model names (e.g., `gpt-5`)
+- GitHub runner types (e.g., `ubuntu-slim`)
+
+## Comment Format (MANDATORY)
+
+Every comment MUST use this exact format: `<emoji> **<severity>:** <description>`
+
+| Severity | Emoji |
+| -------- | ----- |
+| CRITICAL | 🔴    |
+| MODERATE | 🟡    |
+| NIT      | 🟢    |
+
+Examples:
+
+- 🔴 **CRITICAL:** User input is passed directly into the SQL query without parameterization — SQL injection risk. Use a parameterized query instead.
+- 🟡 **MODERATE:** This loops over each item and issues a separate query — N+1 problem. Use a single batch query or a join.
+- 🟢 **NIT:** This nested `if/elif/else` is hard to follow. Consider using early returns to flatten the structure.
+
+## Do NOT Comment On
+
+- Future dates, version numbers, model names, or runner types — your knowledge cutoff makes these unreliable
+- Discrepancies between PR description and code — focus on the code
+- Naming style preferences — only flag actively misleading names
+- Hypothetical or unlikely edge cases — if you'd write "while unlikely", "could potentially", or "edge case where", skip it. Only flag issues that realistically occur in practice.
+- Hardcoded values or magic numbers — do not suggest extracting constants for one-off values

.github/instructions/github-actions.instructions.md

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+---
+applyTo: ".github/workflows/**/*.yml"
+---
+
+# GitHub Actions Code Review Instructions
+
+For workflow style conventions, see [.claude/rules/github-actions.md](../../.claude/rules/github-actions.md).

.github/instructions/python.instructions.md

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+---
+applyTo: "**/*.py"
+---
+
+# Python Code Review Instructions
+
+For style conventions and code examples, see [.claude/rules/python.md](../../.claude/rules/python.md).