docs: index the runnable labs in the repository README

[hellices]

Why

The SRE Agent lab deploys real Azure resources, but nothing in the root README points to it. As more labs land, each one would be equally invisible.

What changed

• root README gains a 🧪 실습 랩 section listing labs that ship their own azure.yaml, with the two facts a reader needs before starting: time and cost
• the section states what qualifies as a lab, so the next one is added to the same table
• test_repo_readme.py keeps the list honest

Why a table and not a generator

One lab today, a handful later. A table costs one row per lab; a generator costs a metadata format and a build step. Revisit if the list outgrows a screen.

Verification

• pytest scripts infra -q — 616 passed
• confirmed the tests fail for the cases they exist to catch: a lab with azure.yaml missing from the table, and a link whose target does not exist

[Copilot]

Pull request overview

This PR makes runnable labs discoverable from the repository root README by adding a dedicated lab index section, and introduces contract tests to ensure the index stays accurate as more labs are added.

Changes:

• Add a new ## 🧪 실습 랩 section in the root README.md with a table that links to runnable labs and captures expected time/cost signals.
• Define what qualifies as a “runnable lab” (presence of azure.yaml) and add guidance for keeping the index updated.
• Add test_repo_readme.py contract tests to enforce: every runnable lab is listed once, links resolve, and key columns are filled.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
README.md	Adds a root-level index section for runnable labs, including time/cost and a link to the lab README.
monitor/sre-agent-event-lab/scripts/tests/test_repo_readme.py	Adds contract tests that validate the root README lab index stays complete, unique, and navigable.

Suppressed comments (1)

monitor/sre-agent-event-lab/scripts/tests/test_repo_readme.py:37

• Consider caching runnable_labs() so REPO_ROOT.rglob("azure.yaml") only runs once per test session (it is called by several tests in this file).

def runnable_labs():
    """Every directory an operator can provision with `azd up`."""
    labs = []
    for azure_yaml in REPO_ROOT.rglob("azure.yaml"):

---

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[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated no new comments.

Suppressed comments (1)

monitor/sre-agent-event-lab/scripts/tests/test_repo_readme.py:53

• Path.read_text() defaults to the system locale encoding. Since the root README contains non-ASCII text (Korean + emoji), this test can fail on environments where the locale isn’t UTF-8 (e.g., some Windows setups). Specify UTF-8 explicitly so the contract test is deterministic across platforms.

def lab_section():
    text = README.read_text()
    assert LAB_SECTION_HEADING in text, (