docs(keycloak-session-store): import the session-storage lab as a new project

The keycloak project ended with four open questions that design could not
settle. A two-VM lab was built to answer them by measurement, and this is
that material: 26 experiments, 125 raw command outputs, 22 browser captures.

Follows the import procedure in README.md.

  source/     the originating repository verbatim — 78 documents, 28 SVGs,
              8 manifests, plus .source-revision recording the commit
  final/      the SSOT
    document.md   729 lines written from the 29 experiment documents, not
                  concatenated: what was predicted, what was measured, and
                  where the measurement itself was wrong
    evidence/raw    125 outputs, flattened to <experiment>__<file> because
                    the originals collided (01-baseline.txt appeared three
                    times) and the audit only globs the top level
    evidence/meta   one per raw file; command and exitCode are null and the
                    README says why rather than inventing them
    evidence/browser  22 captures
    assets/       three diagrams through techviz
    .techviz/     their VizSpecs

A separate project rather than an addition to keycloak: the B-layer answers
that project's four questions, but the A, C and D layers are about cluster
failure, SSO and operations, and one document.md should hold one subject.
The four question records there can point here through 관계.

Recorded rather than papered over: only three of the 28 diagrams were
remade. The repository forbids hand-drawn SVG and forbids titles inside the
canvas; all 28 originals carry both, so converting them is redrawing, not
reformatting. They stay in source/ and the gap is written into the document.

verify-pipeline.py passes. audit-records.py reports no issues.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

docs/clean-architecture-backend-template/final/evidence/raw/273-cloudevents-inbound-id-probe.txt

@@ -0,0 +1,28 @@
+# CloudEvents inbound interop probe
+# revision: 21234e38cdb9a926cbc92bb97a2aee2e4a7d2916
+# cwd: /shared/codebase/clean-architecture-backend-template/src
+# source: /tmp/CeProbe.java (probe only; no repository source was modified)
+# classpath: :messaging:messaging-cloudevents test runtimeClasspath
+# under test: DefaultCloudEventMapper.fromCloudEvent
+# note: CloudEvents 1.0.2 defines id as a non-empty String with no format constraint;
+#       A234-1234-1234 is the id used by the specification own example.
+
+--- spec-conformant opaque string id
+    id = A234-1234-1234
+    result = REJECTED
+    thrown = java.lang.IllegalArgumentException
+    message = Invalid UUID string: A234-1234-1234
+    is a MessagingException (carries FailureDescriptor) = false
+
+--- UUIDv4 id
+    id = 9c1f1f2e-6a1a-4d3b-8f0e-2b0d5b2f6c11
+    result = REJECTED
+    thrown = java.lang.IllegalArgumentException
+    message = a message identity is UUIDv7 (time-ordered); this is version 4
+    is a MessagingException (carries FailureDescriptor) = false
+
+--- UUIDv7 id (what this platform mints)
+    id = 01a0566b-79ca-7000-9e3d-3137b52f4488
+    result = ACCEPTED
+
+# exit=0