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/keycloak-session-store/final/assets/session-sharing-path/session-sharing-path.dot

@@ -0,0 +1,13 @@
+digraph techviz {
+  graph [rankdir=LR, splines=ortho, nodesep=0.55, ranksep=0.85];
+  node [fontname=Helvetica, fontsize=11, margin="0.18,0.12", style="rounded,filled", fillcolor=white, color="#2d4357", penwidth=1.5];
+  edge [fontname=Helvetica, fontsize=10, color="#364b5f", penwidth=1.4, arrowsize=0.75];
+  n0 [label="keycloak-0", shape=box, style="rounded,filled"];
+  n1 [label="PostgreSQL", shape=cylinder, style="rounded,filled"];
+  n2 [label="keycloak-1", shape=box, style="rounded,filled"];
+  n3 [label="JGROUPS_PING", shape=cylinder, style="rounded,filled"];
+  n0 -> n1 [label="세션 INSERT", style=solid];
+  n2 -> n1 [label="세션 SELECT", style=solid];
+  n0 -> n3 [label="멤버 등록", style=solid];
+  n2 -> n3 [label="멤버 등록", style=solid];
+}