Bump MSRV to 1.92, add GCP deployment files (#40)

* Bump MSRV to 1.92 and add GCP deployment files

rig-core 0.30 uses let_chains (stabilized post-1.87), which breaks
builds on Rust 1.85. Bump rust-version in Cargo.toml and both
Dockerfiles to 1.92 (verified working).

Add cloud deployment scaffolding:
- Dockerfile: multi-stage build for the main agent container
- deploy/cloud-sql-proxy.service: systemd unit for Cloud SQL Auth Proxy
- deploy/ironclaw.service: systemd unit for the IronClaw container
- deploy/setup.sh: VM bootstrap script (Docker, proxy, services)
- deploy/env.example: reference environment configuration

Co-Authored-By: Claude Opus 4.6 <[email protected]>

* Address review feedback: harden deploy scaffolding

- Add comment explaining GATEWAY_HOST=0.0.0.0 and when to use 127.0.0.1
- Document /opt/ironclaw ownership model (root-owned, Docker reads as root)
- Switch cloud-sql-proxy service from User=root to DynamicUser=yes

Co-Authored-By: Claude Opus 4.6 <[email protected]>

* fix: Resolve clippy lints (Rust 1.93) and fix CI test workflow

- Fix 97 collapsible_if warnings using let-chains syntax (auto-fixed)
- Fix ptr_arg: change &PathBuf to &Path in pairing store functions
- Fix suspicious_open_options: add .truncate(false) to OpenOptions
- Fix too_many_arguments: add clippy allow on execute_status
- Fix unnecessary_unwrap: use if-let in repository.rs hybrid_search
- Gate unused EchoTool with #[cfg(test)]
- Add PairingStore argument to ChannelStoreData::new() test call sites
- Add skip guard for bundled channel test when WASM artifacts unavailable
- Split CI test workflow to exclude PostgreSQL-dependent integration tests

Co-Authored-By: Claude Opus 4.6 <[email protected]>

* fix: Address review feedback from ilblackdragon

- Add root check to setup.sh (exits with error if not root)
- Add warning comment to env.example about placeholder passwords
- Dockerfile.worker already uses rust:1.92 (no change needed)
- PR #41 overlap noted; will rebase after #41 merges

Co-Authored-By: Claude Opus 4.6 <[email protected]>

* fix: resolve 47 collapsible_if clippy warnings

Collapse nested if statements across the codebase to satisfy
clippy::collapsible_if on Rust 1.93.

Co-Authored-By: Claude Opus 4.6 <[email protected]>

---------

Co-authored-by: Claude Opus 4.6 <[email protected]>

src/agent/session.rs

@@ -346,11 +346,11 @@ impl Thread {
                 let mut turn = Turn::new(turn_number, &msg.content);
 
                 // Check if next is assistant response
-                if let Some(next) = iter.peek() {
-                    if next.role == crate::llm::Role::Assistant {
-                        let response = iter.next().expect("peeked");
-                        turn.complete(&response.content);
-                    }
+                if let Some(next) = iter.peek()
+                    && next.role == crate::llm::Role::Assistant
+                {
+                    let response = iter.next().expect("peeked");
+                    turn.complete(&response.content);
                 }
 
                 self.turns.push(turn);