Modernize str as a pipeline-first string toolkit

Drop all hashing functions (MD5, SHA1, SHA256, HMAC, CRC32, CRC64) and
global mutable state. Rebuild from scratch around a func(string) string
design language where every transformation is composable via str.Pipe.

New API: Pipe, PipeErr, ToSnakeCase, ToCamelCase, ToPascalCase,
ToKebabCase, ToTitleCase, ToScreamingSnake, PadLeft, PadRight, Truncate,
Substring, Wrap, Reverse, CollapseWhitespace, SlugifyASCII, Levenshtein,
JaroWinkler. All rune-based, zero dependencies, no panics, thread-safe.

Adds go.mod, GitHub Actions CI, benchmarks, fuzz testing, 97.5% coverage.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: schigh

.github/workflows/ci.yml

@@ -0,0 +1,37 @@
+name: CI
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        go-version: ['1.24']
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-go@v5
+        with:
+          go-version: ${{ matrix.go-version }}
+      - run: go test -race -coverprofile=coverage.out ./...
+      - run: |
+          COVERAGE=$(go tool cover -func=coverage.out | grep total | awk '{print $3}' | tr -d '%')
+          echo "Coverage: ${COVERAGE}%"
+          if (( $(echo "$COVERAGE < 95" | bc -l) )); then
+            echo "Coverage ${COVERAGE}% is below 95% threshold"
+            exit 1
+          fi
+      - run: go vet ./...
+
+  bench:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-go@v5
+        with:
+          go-version: '1.24'
+      - run: go test -run=^$ -bench=. -benchmem ./...

.travis.yml

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+# Contributing to str
+
+## Design Language
+
+Every transformation function in this library has the signature `func(string) string`. This is the library's identity. It makes every function composable with `Pipe`.
+
+## API Design Rules
+
+Three calling patterns, one decision tree:
+
+1. **Direct** (`func(string) string`) — no configuration needed.
+   - Examples: `ToSnakeCase`, `Reverse`, `CollapseWhitespace`
+
+2. **Partial application** (`func(params) func(string) string`) — 1-2 required parameters.
+   - Examples: `PadLeft(pad, width)`, `Truncate(maxLen, ellipsis)`
+
+3. **Functional options** (`func(required, opts...) func(string) string`) — required param + optional modifiers.
+   - Examples: `Wrap(width, opts...)`
+
+**Decision tree for new functions:**
+- No config? -> Direct
+- All params required, 1-2 params? -> Partial application
+- Required + optional behavior? -> Functional options
+- Not a string transformation? -> Standalone, document clearly
+
+## Naming Conventions
+
+- Transformers: verb form (`Truncate`, `Reverse`, `Wrap`)
+- Case conversions: `To{Format}` (`ToSnakeCase`, `ToCamelCase`)
+- Options: `With{Thing}` for modifiers (`WithLineBreak`), bare name for strategies (`WrapAfterWord`)
+
+## Constraints
+
+- **Zero dependencies.** Stdlib only. No test dependencies either.
+- **No panics.** Every function handles degenerate input gracefully.
+- **Rune-based counting.** All length/width/index parameters count runes, not bytes.
+- **Thread safe.** No shared mutable state.
+
+## Testing
+
+- Table-driven tests using stdlib `testing` only.
+- Every function needs tests for edge cases (empty string, zero values, multibyte input).
+- Every exported function needs a godoc `Example` test.
+- Run `go test -race ./...` before submitting.
+
+## File Organization
+
+One concern per file. Test files mirror source files 1:1. New functions go in the file that matches their category, or get a new file if they don't fit.