feat(demo): funded-wallet restore + build-arg fixes

Adds DEMO_WALLET_SEED/DEMO_WALLET_HEIGHT support so a demo build restores a
fixed (throwaway, funded) Wownero wallet instead of creating a fresh one, via
WalletRestoreViewModel.create. Balance lives on-chain against the seed, so it
survives any emulator wipe and is reproducible.

Three real bugs fixed on the way:
- build-apk.sh built the --dart-define args as a word-split string; the 16-word
  seed's internal spaces split into separate argv tokens and flutter treated a
  seed word as a build target ("Target file '<word>' not found"). Now a bash
  array keeps each --dart-define one token.
- WalletRestoreViewModel.getCredentials reads name/passphrase from the options
  MAP (not the vm field) and casts name as non-null String, so the restore
  options must include 'name' and 'passphrase'.
- forward DEMO_WALLET_SEED/HEIGHT into the build container; source demo.env.

Verified end to end: demo build restores the wallet, its address matches the
funded one exactly (QR-decoded), it syncs at height 861800, and the dashboard
shows the real 13.37 WOW balance + tx history. Send shows Max 13.37.

The seed lives only in gitignored tools/demo/demo.env (never committed).
docs/internal-notes.md (gitignored) documents the FailedDecryption gotcha.

tools/demo/build-apk.sh

@@ -19,6 +19,10 @@
 set -euo pipefail
 
 REPO_ROOT="$(cd "$(dirname "${BASH_SOURCE[0]}")/../.." && pwd)"
+
+# Pull in local capture config (DEMO_WALLET_SEED/HEIGHT/PIN). Gitignored.
+_DEMO_ENV="$(dirname "${BASH_SOURCE[0]}")/demo.env"
+if [[ -f "$_DEMO_ENV" ]]; then set -a; . "$_DEMO_ENV"; set +a; fi
 IMAGE="${CI_IMAGE:-ghcr.io/cake-tech/cake_wallet:debian13-flutter3.32.0-ndkr28-go1.24.1-ruststablenightly}"
 BUILD_MODE="${BUILD_MODE:-debug}"
 ABI="${ABI:-x86_64}"
@@ -47,6 +51,8 @@ docker run --rm \
   -e TARGET_PLATFORM="$TARGET_PLATFORM" \
   -e DEMO="${DEMO:-0}" \
   -e DEMO_PIN="${DEMO_PIN:-0801}" \
+  -e DEMO_WALLET_SEED="${DEMO_WALLET_SEED:-}" \
+  -e DEMO_WALLET_HEIGHT="${DEMO_WALLET_HEIGHT:-0}" \
   -e HOST_UID="$HOST_UID" \
   -e HOST_GID="$HOST_GID" \
   "$IMAGE" bash -c '
@@ -214,17 +220,28 @@ step "compile svg assets"
 ./compile_graphics.sh
 
 step "build apk ($BUILD_MODE / ${TARGET_PLATFORM:-universal})"
-EXTRA=""
-[[ -n "$TARGET_PLATFORM" ]] && EXTRA="--target-platform=$TARGET_PLATFORM"
 # DEMO=1 bakes in DEMO_MODE so the app boots straight to an unlocked demo
 # wallet (kDebugMode-gated, impossible in release). Lets capture skip the
 # onboarding/PIN flow entirely.
-DEMO_DEFINES=""
+# Use an ARRAY, not a string: the seed contains spaces (16 words), so a
+# word-split string turns "--dart-define=DEMO_WALLET_SEED=word1 word2 ..."
+# into separate argv tokens and flutter treats "unlock" as a target file
+# ("Target file 'unlock' not found."). Array elements preserve the spaces.
+DEMO_DEFINES=()
 if [[ "${DEMO:-0}" == "1" ]]; then
-  DEMO_DEFINES="--dart-define=DEMO_MODE=true --dart-define=DEMO_PIN=${DEMO_PIN:-0801}"
-  echo "DEMO_MODE baked in"
+  DEMO_DEFINES+=(--dart-define=DEMO_MODE=true "--dart-define=DEMO_PIN=${DEMO_PIN:-0801}")
+  if [[ -n "${DEMO_WALLET_SEED:-}" ]]; then
+    DEMO_DEFINES+=("--dart-define=DEMO_WALLET_SEED=${DEMO_WALLET_SEED}")
+    DEMO_DEFINES+=("--dart-define=DEMO_WALLET_HEIGHT=${DEMO_WALLET_HEIGHT:-0}")
+    echo "DEMO_MODE baked in (restore from seed, height ${DEMO_WALLET_HEIGHT:-0})"
+  else
+    echo "DEMO_MODE baked in (fresh wallet)"
+  fi
 fi
-flutter build apk --dart-define-from-file=env.json --$BUILD_MODE $EXTRA $DEMO_DEFINES
+EXTRA_ARGS=()
+[[ -n "$TARGET_PLATFORM" ]] && EXTRA_ARGS+=("--target-platform=$TARGET_PLATFORM")
+flutter build apk --dart-define-from-file=env.json --$BUILD_MODE \
+  "${EXTRA_ARGS[@]}" "${DEMO_DEFINES[@]+"${DEMO_DEFINES[@]}"}"
 
 echo
 echo "==> artifacts:"