doc: include previously ignored rule files

Add linting.md and testing.md rules that were hidden by the old
.gitignore pattern.

Co-Authored-By: Claude Opus 4.6 (1M context) <[email protected]>
Signed-off-by: Frederic BIDON <[email protected]>

Author: fredbi

.claude/rules/linting.md

@@ -0,0 +1,17 @@
+---
+paths:
+  - "**/*.go"
+---
+
+# Linting conventions (go-openapi)
+
+```sh
+golangci-lint run
+```
+
+Config: `.golangci.yml` — posture is `default: all` with explicit disables.
+See `docs/STYLE.md` for the rationale behind each disabled linter.
+
+Key rules:
+- Every `//nolint` directive **must** have an inline comment explaining why.
+- Prefer disabling a linter over scattering `//nolint` across the codebase.

.claude/rules/testing.md

@@ -0,0 +1,47 @@
+---
+paths:
+  - "**/*_test.go"
+---
+
+# Testing conventions (go-openapi)
+
+## Running tests
+
+**Single module repos:**
+
+```sh
+go test ./...
+```
+
+**Mono-repos (with `go.work`):**
+
+```sh
+# All modules
+go test work ./...
+
+# Single module
+go test ./conv/...
+```
+
+Note: in mono-repos, plain `go test ./...` only tests the root module.
+The `work` pattern expands to all modules listed in `go.work`.
+
+CI runs tests on `{ubuntu, macos, windows} x {stable, oldstable}` with `-race` via `gotestsum`.
+
+## Fuzz tests
+
+```sh
+# List all fuzz targets
+go test -list Fuzz ./...
+
+# Run a specific target (go test -fuzz cannot span multiple packages)
+go test -fuzz=Fuzz -run='FuzzTargetName$' -fuzztime=1m30s ./package
+```
+
+Fuzz corpus lives in `testdata/fuzz/` within each package. CI runs each fuzz target for 1m30s
+with a 5m minimize timeout.
+
+## Test framework
+
+`github.com/go-openapi/testify/v2` — a zero-dep fork of `stretchr/testify`.
+Because it's a fork, `testifylint` does not work.