fix(quadlet): escape % for systemd specifiers — bitcoind RPC creds were /bin/bash

The creds-off-argv script used printf "rpcuser=%s" in the manifest's
custom_args; quadlet copies Exec= into the generated service's ExecStart,
where systemd expands %s (user's shell) at load time — bitcoind's rpc.conf
came out as rpcuser=/bin/bash and every RPC consumer got 401s on quadlet
nodes (framework-pt: bitcoin-status, HA block-height sensor, LND chain RPC).

Two-layer fix: quadlet.rs now escapes % -> %% in Exec/Entrypoint/HealthCmd/
Environment emission (with regression test), and the bitcoin manifests write
rpc.conf with plain echo so the catalog also heals nodes still running older
binaries. Release catalog regenerated with the fixed scripts.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

apps/bitcoin-core/manifest.yml

@@ -37,7 +37,7 @@ app:
         RPC_PASS="$(printenv BITCOIN_RPC_PASS)";
         RPC_CONF="/tmp/rpc.conf";
         umask 077;
-        printf "rpcuser=%s\nrpcpassword=%s\n" "$RPC_USER" "$RPC_PASS" > "$RPC_CONF";
+        { echo "rpcuser=$RPC_USER"; echo "rpcpassword=$RPC_PASS"; } > "$RPC_CONF";
         RPC_TXRELAY_AUTH="$(printenv BITCOIN_RPC_TXRELAY_RPCAUTH || true)";
         DISK_GB_VALUE="$(printenv DISK_GB || true)";
         RPC_HEADROOM="-rpcthreads=16 -rpcworkqueue=256";

apps/bitcoin-knots/manifest.yml

@@ -37,7 +37,7 @@ app:
         RPC_PASS="$(printenv BITCOIN_RPC_PASS)";
         RPC_CONF="/tmp/rpc.conf";
         umask 077;
-        printf "rpcuser=%s\nrpcpassword=%s\n" "$RPC_USER" "$RPC_PASS" > "$RPC_CONF";
+        { echo "rpcuser=$RPC_USER"; echo "rpcpassword=$RPC_PASS"; } > "$RPC_CONF";
         RPC_TXRELAY_AUTH="$(printenv BITCOIN_RPC_TXRELAY_RPCAUTH || true)";
         DISK_GB_VALUE="$(printenv DISK_GB || true)";
         RPC_HEADROOM="-rpcthreads=16 -rpcworkqueue=256";