fix(install): generate bitcoin RPC password before orchestrator install

Bitcoin containers were exiting in ms after start because the orchestrator
install path skipped the credential-materialisation step the legacy path
did. resolve_secret_env then failed to read
/var/lib/archipelago/secrets/bitcoin-rpc-password, the container started
with no password, and bitcoind crashed before logs were useful.

Two changes:

1. install.rs — call bitcoin_rpc_credentials() for bitcoin/bitcoin-core/
   bitcoin-knots before any install branch runs. The function generates +
   persists on first call (OnceCell-cached), so this is idempotent.

2. manifest.rs::resolve_secret_env — return ManifestError::Invalid when a
   resolved secret trims to empty, instead of silently producing
   `KEY=` env vars that crash auth.

Adds a unit test for the empty-secret rejection.

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

core/container/src/manifest.rs

@@ -619,6 +619,14 @@ impl ContainerConfig {
         let mut out = Vec::with_capacity(self.secret_env.len());
         for e in &self.secret_env {
             let v = provider.read(&e.secret_file)?;
+            // An empty secret produces e.g. `-rpcpassword=` and crashes
+            // the container on auth before logs are useful. Fail loud.
+            if v.trim().is_empty() {
+                return Err(ManifestError::Invalid(format!(
+                    "secret_env {} resolved to empty value (file: {})",
+                    e.key, e.secret_file
+                )));
+            }
             out.push(format!("{}={}", e.key, v));
         }
         Ok(out)
@@ -1051,6 +1059,36 @@ app:
         assert_eq!(out[1], "FM_GATEWAY_PASSWORD=supersecret2");
     }
 
+    #[test]
+    fn resolve_secret_env_rejects_empty_value() {
+        let c = ContainerConfig {
+            image: Some("x:latest".to_string()),
+            image_signature: None,
+            pull_policy: "if-not-present".to_string(),
+            build: None,
+            network: None,
+            custom_args: vec![],
+            entrypoint: None,
+            derived_env: vec![],
+            secret_env: vec![SecretEnv {
+                key: "BITCOIN_RPC_PASS".to_string(),
+                secret_file: "bitcoin-rpc-password".to_string(),
+            }],
+            data_uid: None,
+        };
+        let p = MapSecretsProvider {
+            data: HashMap::from([("bitcoin-rpc-password".to_string(), "   \n".to_string())]),
+        };
+        let err = c.resolve_secret_env(&p).unwrap_err();
+        match err {
+            ManifestError::Invalid(msg) => assert!(
+                msg.contains("BITCOIN_RPC_PASS") && msg.contains("bitcoin-rpc-password"),
+                "msg should name the env key + file: {msg}"
+            ),
+            other => panic!("expected Invalid, got {other:?}"),
+        }
+    }
+
     #[test]
     fn parse_every_real_manifest() {
         let app_manifests = list_repo_manifests();