run-gnome-tests: 'qecore-headless' is not a PyPI package; correct name is 'qecore'

[hanthor]

Problem

The run-gnome-tests WorkflowTemplate (and documentation annotation) references qecore-headless as a Python dependency:

annotations:
  bluefin.io/stack: "qecore-headless + behave + dogtail + gnome-ponytail-daemon"

When the runner falls back to installing Python deps (no requirements.txt in the test suite directory), installing qecore-headless fails:

ERROR: Could not find a version that satisfies the requirement qecore-headless (from versions: none)
ERROR: No matching distribution found for qecore-headless

Root cause

The correct PyPI package name is qecore (not qecore-headless). The smoke test features/environment.py imports from qecore.sandbox and qecore.common_steps, which are part of the qecore package (latest: 4.16).

qecore                 ✓  on PyPI (versions 1.0.x through 4.16)
qecore-headless        ✗  not found on PyPI

Fix

1. Update the bluefin.io/stack annotation to use qecore instead of qecore-headless
2. Add a requirements.txt to each test suite directory (tests/smoke/, tests/developer/, etc.) listing the correct packages so the runner doesn't need a fallback:

   behave
   qecore
   dogtail