Add codespell support with configuration and fixes (#21807)

Co-authored-by: Claude Code 2.1.142 / Claude Opus 4.7 <noreply@anthropic.com>

.codespellrc

@@ -0,0 +1,25 @@
+[codespell]
+
+# Ref: https://github.com/codespell-project/codespell#using-a-config-file
+# Skip historical content (CHANGELOG, release notes archive), auto-generated
+# man pages (which contain troff macros like \(bu that look like typos), and
+# files we don't want to modify (go.sum, css with vendor prefixes).
+skip = .git*,.gitignore,.gitattributes,go.sum,*.css,.codespellrc,CHANGELOG.md,changelog,*.1
+check-hidden = true
+
+# Protect URLs from corrections (URLs may contain words flagged as typos and
+# must not be changed); also ignore camelCase/PascalCase identifiers like
+# AtLeast which are valid Go identifiers, not typos.
+ignore-regex = https?://\S+|\b[a-z]+[A-Z]\w*\b|\b[A-Z][a-z]+[A-Z]\w*\b
+
+ignore-words-list =
+  # variable name short for "serialized", also matches [uU]ser glob pattern
+  ser,
+  # German word "ist" appearing in test data string
+  ist,
+  # intentional truncated test string in format truncation tests
+  fo,
+  # CLI flag name (--iinclude, case-insensitive include)
+  iinclude,
+  # intentional in fake test path /doesnt/exist
+  doesnt