Merge upstream v1.2.20 into the fork

Merges upstream tag v1.2.20 (6aa3dade) into our 1.2.19+sec tree. The merge
base is bc3de30's descendant 9e39a50 -- upstream's own v1.2.19 -- so this is
an ordinary three-way merge, not a replay. Five conflict blocks in four
files, all resolved below.

No consensus change. CheckBlock, ConnectBlock, DisconnectBlock, ConnectInputs,
AcceptBlock, AcceptTransaction, GetNextWorkRequired and GetBlockValue hash
identical to v1.2.19; script.cpp and script.h are byte-identical on both
sides. main.cpp is +3 lines and main.h +2, all wallet-backend plumbing.
rpc.cpp is untouched, so the payout ledger arrives unchanged.

Makefile, VERSION. OURS, renumbered. 1.2.20+sec, for the same reason 1.2.19
carried +sec: this tree is not the upstream release of that number and the
string names every release artifact.

Makefile, AppImage recipe. OURS for the AppDir path, THEIRS for the bundled
library. Upstream's hunk reverts the icon paths to a hardcoded
/tmp/bitflash.AppDir, which is the local-user pre-placement hazard the fork
moved out of /tmp in the first place; taking their side wholesale would have
reintroduced it silently, inside a conflict about something else. The AppDir
stays $(APPDIR), and libsqlite3.so.0 joins the bundled list, which the new
backend genuinely needs.

src/Makefile, src/makefile.mingw, HEADERS. BOTH. Ours drops market.h,
theirs adds wallet_sqlite.h; the resolution does both. NODE_OBJS auto-merged
correctly in both files -- obj/wallet_sqlite.o present, obj/market.o still
gone -- and was verified rather than assumed, because that line has trapped
this fork before.

src/selftest.cpp, known-tests list. BOTH, union. Upstream adds eight
wallet-storage tests, we keep payout-ledger. The dispatch chain itself
auto-merged and still routes payout-ledger to RunPayoutLedgerSelfTest.

Hardening verified intact after merge: the TLS 1.2 floor in nostr.cpp, the
/rvrelay pin, opt-in managed Tor, strict sig3-on-onion descriptor
verification, and the marketplace removal. Upstream shipped no build logs or
__pycache__ this time; the three added files are docs/storage.md and
src/wallet_sqlite.{cpp,h}.

The SQLite backend this release introduces is NOT enabled here. An existing
wallet.dat resolves to Berkeley DB on every branch of the new selection
logic, and the conversion wizard is GUI-only and not compiled into the
headless node. The review findings that gate ever turning it on -- the
non-atomic backend marker, the connection-wide WriteHDMaster transaction,
and the encrypt-swap crash window -- are recorded on the tracker, not fixed
here.

1 files changed, 7 insertions, 5 deletions

diff --git a/Makefile b/Makefile
index 9f97b73..fd4680b 100644
--- a/Makefile
+++ b/Makefile
@@ -11,10 +11,10 @@
 ROOT    := $(shell pwd)
 NPROC   := $(shell nproc 2>/dev/null || echo 2)
 SUDO    := $(shell [ "$$(id -u)" = "0" ] && echo "" || echo "sudo")
-# Not "1.2.19". This tree is upstream v1.2.19 plus our own hardening commits and
+# Not "1.2.20". This tree is upstream v1.2.20 plus our own hardening commits and
 # a hand-merged payout ledger, so a binary built here must not be mistakable for
 # the upstream release of that number -- it names every release artifact.
-VERSION := 1.2.19+sec
+VERSION := 1.2.20+sec
 
 # ---- Pinned third-party sources -------------------------------------------
 #
@@ -82,10 +82,11 @@ deps-apt:
         @if command -v apt-get >/dev/null 2>&1; then \
           $(SUDO) apt-get install -y build-essential cmake git pkg-config autoconf \
             libtool libssl-dev libdb5.3++-dev libsodium-dev nlohmann-json3-dev \
-            libboost-system-dev libglfw3-dev libgl-dev python3-pil clang; \
+            libboost-system-dev libglfw3-dev libgl-dev libsqlite3-dev \
+            python3-pil clang; \
         else \
           echo "Not an apt system — install: g++ cmake git autoconf libtool"; \
-          echo "  libssl libdb++ libsodium nlohmann-json boost glfw3 opengl python3-pil"; \
+          echo "  libssl libdb++ libsodium nlohmann-json boost glfw3 opengl sqlite3 python3-pil"; \
         fi
 
 deps-secp256k1:
@@ -172,7 +173,7 @@ img = ico.convert('RGBA'); \
 img.save(d + '/bitflash.png'); \
 import shutil; shutil.copy(d + '/bitflash.png', \
 d + '/usr/share/icons/hicolor/256x256/apps/bitflash.png')"
-        @for lib in libsodium.so.23 libdb_cxx-5.3.so libglfw.so.3; do \
+        @for lib in libsodium.so.23 libdb_cxx-5.3.so libsqlite3.so.0 libglfw.so.3; do \
           path=$$(ldconfig -p | grep " $$lib " | awk '{print $$NF}' | head -1); \
           [ -z "$$path" ] && path=$$(find /usr/lib /lib -name "$$lib" 2>/dev/null | head -1); \
           [ -n "$$path" ] && cp -L "$$path" $(APPDIR)/usr/lib/ && echo "  bundled $$lib" || echo "  missing $$lib"; \
@@ -190,6 +191,7 @@ deps-windows:
           mingw-w64-ucrt-x86_64-glfw \
           mingw-w64-ucrt-x86_64-openssl \
           mingw-w64-ucrt-x86_64-db \
+          mingw-w64-ucrt-x86_64-sqlite3 \
           mingw-w64-ucrt-x86_64-libsodium \
           mingw-w64-ucrt-x86_64-nlohmann-json \
           mingw-w64-ucrt-x86_64-boost \