Add basic claude infrastructure

Author: hadley

.claude/CLAUDE.md

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+## R package development
+
+### Key commands
+
+```
+# To run code
+Rscript -e "devtools::load_all(); code"
+
+# To run all tests
+Rscript -e "devtools::test()"
+
+# To run tests for R/{name.R}
+Rscript -e "devtools::test(filter = '{name}', reporter = 'llm')"
+
+# To document the package
+Rscript -e "devtools::document()"
+
+# To check pkgdown documentation
+Rscript -e "pkgdown::check_pkgdown()"
+
+# To format code
+air format .
+```
+
+### Coding
+
+* Always run `air format .` after generating code
+* Use the base pipe operator (`|>`) not the magrittr pipe (`%>%`)
+* Don't use `_$x` or `_$[["x"]]` since dbplyr must work on R 4.1.
+* Use `\() ...` for single-line anonymous functions. For all other cases, use `function() {...}` 
+
+### Testing
+
+- Tests for `R/{name}.R` go in `tests/testthat/test-{name}.R`. 
+- All new code should have an accompanying test.
+- If there are existing tests, place new tests next to similar existing tests.
+- Strive to keep your tests minimal with few comments.
+
+### Documentation
+
+- Every user-facing function should be exported and have roxygen2 documentation.
+- Wrap roxygen comments at 80 characters.
+- Internal functions should not have roxygen documentation.
+- Whenever you add a new documentation topic, also add the topic to `_pkgdown.yml`. 
+- Use `pkgdown::check_pkgdown()` to check that all topics are included in the reference index.
+
+### Writing
+
+- Use sentence case for headings.
+
+### Proofreading
+
+If the user asks you to proofread a file, act as an expert proofreader and editor with a deep understanding of clear, engaging, and well-structured writing. 
+
+Work paragraph by paragraph, always starting by making a TODO list that includes individual items for each top-level heading. 
+
+Fix spelling, grammar, and other minor problems without asking the user. Label any unclear, confusing, or ambiguous sentences with a FIXME comment.
+
+Only report what you have changed.

.claude/settings.json

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+{
+  "$schema": "https://json.schemastore.org/claude-code-settings.json",
+  "permissions": {
+    "allow": [
+      "Bash(find:*)",
+      "Bash(Rscript:*)",
+      "Bash(rm:*)",
+      "Bash(air format:*)",
+      "Edit(R/**)",
+      "Edit(tests/**)",
+      "Edit(vignettes/**)",
+    ],
+    "deny": []
+  }
+}