Move the processing code under pipeline/

Preparing to merge this repository into a combined astrophotography
repo. session-scripts/ becomes pipeline/ because the scripts import
layout.py from their own directory and must stay together, and because
'pipeline' says what it is rather than how it came about. observing/
stays at the top level: observing plans are not processing code.

session-scripts/unzip.py

@@ -1,33 +0,0 @@
-"""Uncompress every calibrated-*.zip in the session folder, in place.
-
-iTelescope ships each calibrated frame as a one-entry zip (.fit.zip and
-.tif.zip). Extraction is skipped when the target already exists and is
-non-empty, so this is safe to re-run.
-"""
-import glob
-import os
-import zipfile
-
-import layout
-
-SRC = layout.SESSION
-
-zips = sorted(glob.glob(layout.path("calibrated-*.zip")))
-print(f"{len(zips)} calibrated archives")
-done = skipped = 0
-for z in zips:
-    with zipfile.ZipFile(z) as zf:
-        for info in zf.infolist():
-            target = layout.path(os.path.basename(info.filename))
-            if os.path.exists(target) and os.path.getsize(target) == info.file_size:
-                skipped += 1
-                continue
-            with zf.open(info) as fsrc, open(target, "wb") as fdst:
-                while chunk := fsrc.read(1 << 20):
-                    fdst.write(chunk)
-            done += 1
-print(f"extracted {done}, already present {skipped}")
-
-for ext in (".fit", ".tif"):
-    n = len(glob.glob(layout.path(f"calibrated-*{ext}")))
-    print(f"{ext}: {n} files")