fix(non-interactive-env): add Windows/PowerShell support (#573)

* fix(non-interactive-env): add Windows/PowerShell support

- Create shared shell-env utility with cross-platform shell detection
- Detect shell type via PSModulePath, SHELL env vars, platform fallback
- Support Unix (export), PowerShell ($env:), and cmd.exe (set) syntax
- Add 41 comprehensive unit tests for shell-env utilities
- Add 5 cross-platform integration tests for hook behavior
- All 696 tests pass, type checking passes, build succeeds

Closes #566

* fix: address review feedback - add isNonInteractive check and cmd.exe % escaping

- Add isNonInteractive() check to only apply env vars in CI/non-interactive contexts (Issue #566)
- Fix cmd.exe percent sign escaping to prevent environment variable expansion
- Update test expectations for correct % escaping behavior

Resolves feedback from @greptile-apps and @cubic-dev-ai

---------

Co-authored-by: sisyphus-dev-ai <sisyphus-dev-ai@users.noreply.github.com>

src/shared/shell-env.ts

@@ -0,0 +1,111 @@
+export type ShellType = "unix" | "powershell" | "cmd"
+
+/**
+ * Detect the current shell type based on environment variables.
+ * 
+ * Detection priority:
+ * 1. PSModulePath → PowerShell
+ * 2. SHELL env var → Unix shell
+ * 3. Platform fallback → win32: cmd, others: unix
+ */
+export function detectShellType(): ShellType {
+  if (process.env.PSModulePath) {
+    return "powershell"
+  }
+
+  if (process.env.SHELL) {
+    return "unix"
+  }
+
+  return process.platform === "win32" ? "cmd" : "unix"
+}
+
+/**
+ * Shell-escape a value for use in environment variable assignment.
+ * 
+ * @param value - The value to escape
+ * @param shellType - The target shell type
+ * @returns Escaped value appropriate for the shell
+ */
+export function shellEscape(value: string, shellType: ShellType): string {
+  if (value === "") {
+    return shellType === "cmd" ? '""' : "''"
+  }
+
+  switch (shellType) {
+    case "unix":
+      if (/[^a-zA-Z0-9_\-.:\/]/.test(value)) {
+        return `'${value.replace(/'/g, "'\\''")}'`
+      }
+      return value
+
+    case "powershell":
+      return `'${value.replace(/'/g, "''")}'`
+
+    case "cmd":
+      // Escape % first (for environment variable expansion), then " (for quoting)
+      return `"${value.replace(/%/g, '%%').replace(/"/g, '""')}"`
+
+    default:
+      return value
+  }
+}
+
+/**
+ * Build environment variable prefix command for the target shell.
+ * 
+ * @param env - Record of environment variables to set
+ * @param shellType - The target shell type
+ * @returns Command prefix string to prepend to the actual command
+ * 
+ * @example
+ * ```ts
+ * // Unix: "export VAR1=val1 VAR2=val2; command"
+ * buildEnvPrefix({ VAR1: "val1", VAR2: "val2" }, "unix")
+ * // => "export VAR1=val1 VAR2=val2;"
+ * 
+ * // PowerShell: "$env:VAR1='val1'; $env:VAR2='val2'; command"
+ * buildEnvPrefix({ VAR1: "val1", VAR2: "val2" }, "powershell")
+ * // => "$env:VAR1='val1'; $env:VAR2='val2';"
+ * 
+ * // cmd.exe: "set VAR1=val1 && set VAR2=val2 && command"
+ * buildEnvPrefix({ VAR1: "val1", VAR2: "val2" }, "cmd")
+ * // => "set VAR1=\"val1\" && set VAR2=\"val2\" &&"
+ * ```
+ */
+export function buildEnvPrefix(
+  env: Record<string, string>,
+  shellType: ShellType
+): string {
+  const entries = Object.entries(env)
+  
+  if (entries.length === 0) {
+    return ""
+  }
+
+  switch (shellType) {
+    case "unix": {
+      const assignments = entries
+        .map(([key, value]) => `${key}=${shellEscape(value, shellType)}`)
+        .join(" ")
+      return `export ${assignments};`
+    }
+
+    case "powershell": {
+      const assignments = entries
+        .map(([key, value]) => `$env:${key}=${shellEscape(value, shellType)}`)
+        .join("; ")
+      return `${assignments};`
+    }
+
+    case "cmd": {
+      const assignments = entries
+        .map(([key, value]) => `set ${key}=${shellEscape(value, shellType)}`)
+        .join(" && ")
+      return `${assignments} &&`
+    }
+
+    default:
+      return ""
+  }
+}