test: Tier 0-2 scaffolding (shell syntax, imports, entrypoints, runner metadata)

[cailmdaley]

Summary

Scaffold a cheap, broad test suite that gates PRs to develop. The goal is to catch the kind of bugs we've hit repeatedly in recent reviews — bash syntax errors (#706 `init_run_v2.0.sh`), module-level import of optional deps that makes a `try/except` unreachable (#699 `coverage_map_builder.py`), broken `[project.scripts]` entry points, runners missing `@module_runner` metadata, docker image upstream drift (#707 skyproj/PROJ).

What's covered

File	Catches
`tests/unit/test_shell_syntax.py`	`bash -n` over every `scripts/sh/*.{sh,bash}` — unclosed quotes, unbalanced brackets, stray parens
`tests/unit/test_config_parse.py`	configparser over every `example/**/*.ini` — malformed section headers, duplicate keys
`tests/unit/test_imports.py`	Import every `shapepipe.*` submodule — syntax errors, typos, unreachable `except ImportError`
`tests/unit/test_entrypoints.py`	`<script> -h` on every `[project.scripts]` entry — broken targets, args mishandled
`tests/unit/test_runner_metadata.py`	Every `*_runner.py` exports a function decorated with `@module_runner`

Each test is parametrized one-case-per-file, so the CI output names exactly which script/module/runner is at fault.

Pre-existing failures

These surfaced when the suite first ran on `develop`. Tracked as `xfail(strict=True)` so the PR lands green and the failure re-surfaces as a loud `XPASSED` once fixed:

• `stile v0.1` imports removed `treecorr.corr2` — breaks `mccd_plots_runner`, `random_cat_runner`, and their packages. Upstream issue; fixable by bumping stile or constraining treecorr.
• `summary_run -h` treats `-h` as the `patch` positional and tries to `os.mkdir('-h')`. Argparse-adjustment needed in `scripts/python/summary_run.py`.

Plumbing fixes

• `pyproject.toml` — `testpaths = ["shapepipe"]` was stale from before the `src` layout migration. Fixed to `["tests", "src/shapepipe/tests"]` so pytest actually discovers these.
• New workflow `.github/workflows/ci-dev.yml` runs the unit suite on PRs to `develop` using the published `ghcr.io/cosmostat/shapepipe:develop` image. The existing `ci-release.yml` keeps gating main/master unchanged.

Local run

Inside the shapepipe container:
```
pytest tests/unit/ -v --no-cov -p no:warnings

196 passed, 3 skipped, 7 xfailed in 5.16s

```
(The 3 skips are `canfar_*` commands absent from an older local container; present in the CI image.)

Test plan

• CI (develop) workflow runs green on this PR
• Merge; verify next PR to develop triggers the workflow

🤖 Generated with Claude Code

[cailmdaley]

CI caught more failures than the local pre-#702 container did — all expected, all now xfailed. Filed issues for follow-up:

• canfar_monitor.py: IndentationError at line 55 breaks canfar_run and 3 entry points #709 canfar_monitor.py:55 IndentationError (breaks canfar_run + 3 entry points)
• stile v0.1 import fails: 'treecorr.corr2' removed in newer treecorr #710 stile v0.1 importing removed treecorr.corr2 (breaks 4 modules)
• summary_run -h crashes: '-h' parsed as 'patch' positional #711 summary_run -h crashes
• Dockerfile missing runtime deps for newly-merged modules (astroquery, numba, fitsio) #712 Dockerfile missing runtime deps (astroquery / numba / fitsio)

These are all pre-existing on develop — the scaffolding exposed them. Each xfail carries a `reason=` pointing at the issue so the linkage stays visible. `strict=True` auto-flips to XPASSED when any of these get fixed.