re: where .prt screen parts live; the five mission banners are a real exception

Read first, as the rule now requires: ui-prm-primitives.md,
ui-rat-layout.md, ui-screen-runtime.md -- they own the .prt/RATC/T8aD
stack but describe element names inside bundles, not where parts live.

A .prt IS a pak entry, under a LANGUAGE directory.  Of 376 distinct
.prt names referenced on the disc, 241 resolve as archive entries --
220 under eng\ and jpn\, 38 under each of the other four.  prbase.prt
resolves under all six; palogo1.prt under two.

All five pgmsg_*.prt resolve under nothing, across 15 prefixes that
include every language dir, so this is not the missing-prefix mistake
again.

A lead, refuted by its own control: four of the five have a same-stem
_sub.rat sub-bundle inside every per-language 2D pak, and pgmsg_update
has none -- but only 4 of 376 .prt stems have a _sub.rat, and
prbase.prt, which does ship as an entry, has none.  Not the container
convention, not adopted.

An intermediate pass nearly reported 'the five appear only in the
manifest'; that was wrong because the token census was truncated by a
slice and the RATC hits were pgmsg_start_sub.rat, a longer token.

New artefact and regenerator; the other six regenerate byte-identical.

tools/re-capture/prt_parts.py

@@ -0,0 +1,64 @@
+#!/usr/bin/env python3
+"""Where `.prt` screen parts live, and why the five mission banners do not.
+
+Regenerates docs/re/data/prt-parts.txt.
+"""
+import sys, os, glob, re, collections
+
+HERE = os.path.dirname(os.path.abspath(__file__))
+sys.path.insert(0, HERE)
+import unitgroup as U
+from unit_substructures import pak_entries
+
+FIVE = ['pgmsg_start.prt', 'pgmsg_end.prt', 'pgmsg_update.prt',
+        'pgmsg_failed.prt', 'pgmsg_restart.prt']
+PRE = ['', 'Stage\\', 'stage\\', 'message\\', 'language\\', '2d\\', 'ui\\', 'prt\\',
+       'view\\'] + [l + '\\' for l in ('eng', 'jpn', 'fra', 'deu', 'ita', 'esp')]
+
+def main():
+    H = collections.defaultdict(set)
+    names = set()
+    rat = collections.defaultdict(set)
+    for pk in sorted(glob.glob('/work/sylph_extract/**/*.pak', recursive=True)):
+        base = os.path.basename(pk)
+        for h, b in pak_entries(pk):
+            H[h].add(base)
+            for m in re.finditer(rb'[A-Za-z0-9_]{3,40}\.prt', b):
+                names.add(m.group(0).decode())
+            if b[:4] == b'RATC':
+                for m in re.finditer(rb'[A-Za-z0-9_]{3,40}_sub\.rat', b):
+                    rat[m.group(0).decode()].add(base)
+
+    print("# Where `.prt` screen parts live")
+    print("# Regenerate: python3 tools/re-capture/prt_parts.py")
+    print("# See docs/re/structures/mission-script-manifest.md")
+
+    byp = collections.Counter()
+    hit = set()
+    for n in names:
+        for p in PRE:
+            if U.name_hash(p + n) in H:
+                byp[p] += 1; hit.add(n)
+    print("\n## `.prt` IS a pak entry name -- under a LANGUAGE directory")
+    print("   distinct .prt names referenced anywhere : %d" % len(names))
+    print("   resolving as a pak entry                : %d" % len(hit))
+    for p, c in byp.most_common():
+        print("        prefix %-8s %3d" % (repr(p), c))
+
+    print("\n## the five mission-banner parts")
+    for n in FIVE + ['prbase.prt', 'palogo1.prt']:
+        ok = [p or '<bare>' for p in PRE if U.name_hash(p + n) in H]
+        print("   %-20s resolves under: %s" % (n, ok if ok else 'NOTHING'))
+
+    print("\n## `<stem>_sub.rat` sub-bundles inside RATC")
+    print("   distinct _sub.rat names: %d" % len(rat))
+    for k in sorted(rat):
+        print("        %-26s in %d archives  %s" % (k, len(rat[k]), sorted(rat[k])[:2]))
+    stems_prt = {n[:-4] for n in names}
+    stems_rat = {k[:-8] for k in rat}
+    print("   CONTROL  .prt stems that have a _sub.rat: %d / %d -- so this is NOT the general"
+          % (len(stems_prt & stems_rat), len(stems_prt)))
+    print("            container convention; `prbase` has a .prt entry and no _sub.rat.")
+
+if __name__ == "__main__":
+    main()