Session 0018.0 (Wave 9): rewrite legacy session refs in transcript bodies + README scoping

- Rewrite every legacy `Session L` / `Session M.1` etc. reference inside
  transcript bodies to the numeric form (`Session 0012.0` / `Session 0013.1`),
  via a mechanical Python sed pass scoped to canonical-filename transcripts
  only (502 replacements across 39 files; 21 files in this published repo +
  18 sibling files in `~/git/ohm-infra/`). The §23 rename was originally
  filename-only — session 0018.0 reverses that and rewrites the bodies too,
  so cross-references inside a transcript match the filename you'd browse
  to. The mapping table (`A → 0001` … `N → 0014`) lives in
  `SESSION-PROTOCOL.md` §1 (also amended this session) for anyone hitting
  an old external link.

- Amend README.md:
  - New "Where the record begins" section noting OHM started with two
    vibe-coded prototypes (no transcripts; the discipline that produced this
    record didn't exist yet). The transcripts here begin at the
    spec-driven-development phase — not at the literal beginning of OHM.
  - Update the existing "Sessions 0001 through 0013 originally shipped
    under a letter-form naming" paragraph to reflect that body refs are
    now also in numeric form.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

0004/SESSION-0004.0-TRANSCRIPT-2026-05-27T15-30--2026-05-27T16-47.md

@@ -1,4 +1,4 @@
-# Session D — Transcript
+# Session 0004.0 — Transcript
 
 > Date: 2026-05-27
 > Goal: Write `flotilla/SPEC.md` (binding architectural contract for
@@ -44,7 +44,7 @@
 > scope for v1 (private-branch deploys, multi-deployment beyond OHM,
 > Cloud Build, auto-deploy on merge); required reading list
 > (rfc-app/CLAUDE.md, rfc-app/SPEC.md §17/§19.2/§19.3/§20,
-> ohm-infra/SESSION-C-TRANSCRIPT.md Turn 22/29/33, deploy/RUNBOOK.md
+> ohm-infra/SESSION-0003.0-TRANSCRIPT.md Turn 22/29/33, deploy/RUNBOOK.md
 > and DEPLOY-NEW-SESSION-PROMPT.md, ohm-rfc/.rfc-app-version,
 > flotilla/ currently empty); the session-step plan (cleanup first,
 > then spec with 14 required sections, then don't migrate secrets in
@@ -57,7 +57,7 @@
 The assistant began by reading the required context in parallel:
 `rfc-app/SPEC.md` for §17 (the `/api/health` contract), §19.2/§19.3
 (candidate topics + working agreement shape), §20 (versioning policy);
-`ohm-infra/SESSION-C-TRANSCRIPT.md` Turns 22, 29, 33 (the Option 2
+`ohm-infra/SESSION-0003.0-TRANSCRIPT.md` Turns 22, 29, 33 (the Option 2
 secret-store commitment and the `ohm-app` naming convention);
 `rfc-app/deploy/RUNBOOK.md` (the manual upgrade sequence flotilla
 would automate); the current `.rfc-app-version` pin (`0.3.0`); the
@@ -838,8 +838,8 @@ Wrote a corresponding `MEMORY.md` index pointing at the four.
 ## Turn 33 — Assistant
 
 This file. The assistant inspected the existing
-`SESSION-C-TRANSCRIPT.md` for naming convention and style, then
-wrote this `SESSION-D-TRANSCRIPT.md` reproducing every turn of the
+`SESSION-0003.0-TRANSCRIPT.md` for naming convention and style, then
+wrote this `SESSION-0004.0-TRANSCRIPT.md` reproducing every turn of the
 session.
 
 ## Turn 34 — User
@@ -918,10 +918,10 @@ Treated as the session-close moment. Gave a recap of what landed
 (GCP cleanup; v0.0.1 spec at canonical-only `a9a9aaa`; memory
 synced; full transcript exists) and three options:
 
-1. Start Session E — Slice 1 now (primary cwd
+1. Start Session 0005.0 — Slice 1 now (primary cwd
    `/Users/benstull/git/ohm-rfc-app-flotilla/`, additional dir
    `/Users/benstull/git/rfc-app/`, the §20.1 brief).
-2. Step away — Session D is a complete unit of work.
+2. Step away — Session 0004.0 is a complete unit of work.
 3. One more small thing in this session — investigate the
    `{"detail":"Not Found"}` on ohm.wiggleverse.org/api/health, or
    clean up rfc-app's dirty working tree, or move rfc-app's
@@ -1039,7 +1039,7 @@ Verified the dir contents: `MEMORY.md` + four memory files
 This update. Captures Turns 40 and 41 themselves and confirms the
 session genuinely closes here. The operator's next move is to
 `cd /Users/benstull/projects/wiggleverse/ohm-rfc-app-flotilla/`
-and start a fresh `claude` session for Session E — Slice 1.
+and start a fresh `claude` session for Session 0005.0 — Slice 1.
 
 Final task list at session close (now actually final):
 
@@ -1085,7 +1085,7 @@ Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
     - SQLite state at ~/.ohm-rfc-app-flotilla/ohm-rfc-app-flotilla.db.
     - Secret bytes never live in flotilla — GCP Secret Manager holds
       bytes, flotilla holds references (Option 2 from the rfc-app/OHM
-      Session C transcript).
+      Session 0003.0 transcript).
     - Deploy verification via the rfc-app/SPEC.md §17 /api/health
       endpoint (version-match check).
     - Operator-triggered only; no auto-deploy in v1.
@@ -1262,6 +1262,6 @@ At end of session, those four memory files plus
 copied into a fresh
 `/Users/benstull/.claude/projects/-Users-benstull-git-ohm-rfc-app-flotilla/memory/`
 directory with a corresponding `MEMORY.md` index, so the next
-session (Session E — Slice 1, with primary cwd
+session (Session 0005.0 — Slice 1, with primary cwd
 `/Users/benstull/projects/wiggleverse/ohm-rfc-app-flotilla/`) auto-loads them
 without manual setup.