docs: two corrections from the convention owner and the spec owner

Both arrived within minutes of the v0.4.0 announcement and both change
what we would otherwise have built or claimed.

CATALOG -- a profile field we must NOT add. Their steg 5 measured bundle
placement across four consumers: exactly one installs a bundle anywhere,
the other three take the bundle directory as a per-run argument with no
default, no discovery and no $HOME expansion. Placement is unmandated, so
BundleProfile gets no root-location or install-path field, "no
installation root" is a conforming consumer shape, and write policy must
not be coupled to placement. Recorded in the split table, which also now
spells the proving consumer's layer prefixes bundle-relative
(concepts/, releases/) rather than repeating the bundle/ prefix their own
repository layout carries -- that prefix was placement leaking into a
contract.

COMMONS -- our "Fixed" framing outruns their frozen text. Removing every
ingest-stamped file is verbatim what ingest-spec v1 section 5 mandates:
v1 assumes one manifest per bundle and defers the multi-manifest case as
a named extension point. So v0.4.0 implements that extension point rather
than fixing a defect against the spec. The mechanic survives ratification
either way -- stem matching follows from their own {stem}@{h} stamp
definition, since {h} changes on every content edit -- but the prose is
queued for amendment and is not ratified, so the changelog now says so
instead of claiming conformance it does not have.

CHANGELOG.md

@@ -90,6 +90,17 @@ and with them this library's first — and only ever — runtime dependency.
 - Phase 2's binary extraction is **not** in this release: the `[extract]`
   extra is declared but empty, and `pdf`/`docx`/`xlsx` therefore fail fast.
   That is the one outstanding item from the phase, and it ships separately.
+- **The ownership change above is an extension point, not a spec fix.** Filed
+  under "Fixed" because it stops silent data loss, but the spec owner
+  (`portfolio-optimiser-commons`) has since pointed out that removing *every*
+  ingest-stamped file is verbatim what ingest-spec v1 §5 mandates: v1 assumes
+  one manifest per bundle and defers multiple manifests feeding one bundle as
+  a named extension point. So this release implements that extension point and
+  outruns the frozen text rather than conforming to it. The mechanic itself is
+  not at risk — matching by manifest stem follows from the spec's own
+  `{stem}@{h}` stamp definition, since `{h}` changes on every content edit —
+  but the surrounding prose is queued for amendment in commons and is not
+  ratified. Treat multi-manifest bundles as ahead of the spec until it is.
 - Exception `__cause__` preservation is now pinned by a conformance suite, one
   test per fail-fast wrap site, alongside the existing `.code` suite.