#30: per-session folder layout + README + sessions.json

Restructures the flat repo into one folder per session, with a top-level
README.md (the "about sessions" page, also rendered at /docs/sessions/about
by rfc-app v0.19.0+) and a sessions.json title manifest keyed by 4-digit
NNNN. Filenames inside each folder retain the full SESSION-NNNN.M-TRANSCRIPT-…
form (no trim of the SESSION- prefix). Legacy letter-form transcripts, if
any are still at the root, are not moved — the folder convention applies
to the numeric form only.

Session 0017.0; see SESSION-PROTOCOL.md §1 amendment for the binding shape.

sessions.json

@@ -0,0 +1,17 @@
+{
+  "0001": { "title": "Bootstrap — git.benstull.org personal Gitea on GCP" },
+  "0002": { "title": "Session B — first OHM deployment (ohm.wiggleverse.org from zero)" },
+  "0003": { "title": "Session C — rfc-app 0.3.0 release + OHM upgrade (allowlist + anon read)" },
+  "0004": { "title": "Session D — flotilla SPEC + rfc.wiggleverse.org deprovision" },
+  "0005": { "title": "Session E — flotilla Slices 1 & 2 (registry + overlay; secret refs)" },
+  "0006": { "title": "Session F — flotilla Slice 3 (pin reading + deploy --dry-run, v0.3.0)" },
+  "0007": { "title": "Session G — flotilla Slice 4 (full deploy gesture + health probe, v0.4.0)" },
+  "0008": { "title": "Session H — flotilla v1.0.0 + first real OHM upgrade via flotilla" },
+  "0009": { "title": "Session I — multi-wave driver (rfc-app v0.4–v0.13, skipping vacants)" },
+  "0010": { "title": "Session J — DOCS.md + /docs route (rfc-app v0.14.0)" },
+  "0011": { "title": "Session K — Wave 4 (admin /users, device trust, CloudFlare Turnstile)" },
+  "0012": { "title": "Session L — Wave 5 (Amplitude, owner-invite, admin-create)" },
+  "0013": { "title": "Session M — Wave 6 (CONTRIBUTING + SPEC §21 analytics; repo-naming; email/webhook runbook)" },
+  "0014": { "title": "Session N — Wave 7 driver (SMTP + webhook hardening, #23 transcript rename)" },
+  "0015": { "title": "Roadmap-capture parallel session (items #24–#30 added to ROADMAP.md)" }
+}