Add configurable timeout and retry for git network operations

Add per-attempt timeout (default 300s) and Kubernetes probe-style retry
configuration for git fetch, lfs-fetch, and ls-remote. New action inputs:
timeout, retry-max-attempts, retry-min-backoff, retry-max-backoff.

Fixes https://github.com/actions/checkout/issues/631

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

src/input-helper.ts

@@ -161,5 +161,41 @@ export async function getInputs(): Promise<IGitSourceSettings> {
   result.githubServerUrl = core.getInput('github-server-url')
   core.debug(`GitHub Host URL = ${result.githubServerUrl}`)
 
+  // Timeout (per-attempt, like k8s timeoutSeconds)
+  result.timeout = Math.floor(Number(core.getInput('timeout') || '300'))
+  if (isNaN(result.timeout) || result.timeout < 0) {
+    result.timeout = 300
+  }
+  core.debug(`timeout = ${result.timeout}`)
+
+  // Retry max attempts (like k8s failureThreshold)
+  result.retryMaxAttempts = Math.floor(
+    Number(core.getInput('retry-max-attempts') || '3')
+  )
+  if (isNaN(result.retryMaxAttempts) || result.retryMaxAttempts < 1) {
+    result.retryMaxAttempts = 3
+  }
+  core.debug(`retry max attempts = ${result.retryMaxAttempts}`)
+
+  // Retry backoff (like k8s periodSeconds, but as a min/max range)
+  result.retryMinBackoff = Math.floor(
+    Number(core.getInput('retry-min-backoff') || '10')
+  )
+  if (isNaN(result.retryMinBackoff) || result.retryMinBackoff < 0) {
+    result.retryMinBackoff = 10
+  }
+  core.debug(`retry min backoff = ${result.retryMinBackoff}`)
+
+  result.retryMaxBackoff = Math.floor(
+    Number(core.getInput('retry-max-backoff') || '20')
+  )
+  if (isNaN(result.retryMaxBackoff) || result.retryMaxBackoff < 0) {
+    result.retryMaxBackoff = 20
+  }
+  if (result.retryMaxBackoff < result.retryMinBackoff) {
+    result.retryMaxBackoff = result.retryMinBackoff
+  }
+  core.debug(`retry max backoff = ${result.retryMaxBackoff}`)
+
   return result
 }