build: fixes local runnability of itk tests and adds readme on how to setup (#946)

# Description

PR fixes ability to run itk tests locally and adds readme with proper
instructions on how to set up the environment for that.

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Fixes #<issue_number_goes_here> 🦕

Co-authored-by: Krzysztof Dziedzic <dziedzick@google.com>
Co-authored-by: Ivan Shymko <ishymko@google.com>

Author: 3 people

.github/actions/spelling/allow.txt

@@ -138,3 +138,8 @@ TResponse
 typ
 typeerror
 vulnz
+Podman
+podman
+UIDs
+subuids
+subgids

itk/README.md

@@ -0,0 +1,54 @@
+# Running ITK Tests Locally
+
+This directory contains scripts to run Integration Test Kit (ITK) tests locally using Podman.
+
+## Prerequisites
+
+### 1. Install Podman
+
+Run the following commands to install Podman and its components:
+
+```bash
+sudo apt update && sudo apt install -y podman podman-docker podman-compose
+```
+
+### 2. Configure SubUIDs/SubGIDs
+
+For rootless Podman to function correctly, you need to ensure subuids and subgids are configured for your user.
+
+If they are not already configured, you can add them using (replace `$USER` with your username if needed):
+
+```bash
+sudo usermod --add-subuids 100000-165535 --add-subgids 100000-165535 $USER
+```
+
+After adding subuids or if you encounter permission issues, run:
+
+```bash
+podman system migrate
+```
+
+## Running Tests
+
+### 1. Set Environment Variable
+
+You must set the `A2A_SAMPLES_REVISION` environment variable to specify which revision of the `a2a-samples` repository to use for testing. This can be a branch name, tag, or commit hash.
+
+Example:
+```bash
+export A2A_SAMPLES_REVISION=itk-v.0.11-alpha
+```
+
+### 2. Execute Tests
+
+Run the test script from this directory:
+
+```bash
+./run_itk.sh
+```
+
+The script will:
+- Clone `a2a-samples` (if not already present).
+- Checkout the specified revision.
+- Build the ITK service Docker image.
+- Run the tests and output results.

itk/run_itk.sh

@@ -70,8 +70,9 @@ docker run -d --name itk-service \
   itk_service
 
 # 5.1. Fix dubious ownership for git (needed for uv-dynamic-versioning)
-docker exec itk-service git config --global --add safe.directory /app/agents/repo
-docker exec itk-service git config --global --add safe.directory /app/agents/repo/itk
+docker exec -u root itk-service git config --system --add safe.directory /app/agents/repo
+docker exec -u root itk-service git config --system --add safe.directory /app/agents/repo/itk
+docker exec -u root itk-service git config --system core.multiPackIndex false
 
 # 6. Verify service is up and send post request
 MAX_RETRIES=30