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]>

Dockerfile.worker

@@ -9,7 +9,7 @@
 # The image includes common development tools so workers can build software,
 # run tests, and execute shell commands.
 
-FROM rust:1.85-bookworm AS builder
+FROM rust:1.92-bookworm AS builder
 
 WORKDIR /build
 COPY . .
@@ -40,7 +40,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
 ENV RUSTUP_HOME=/usr/local/rustup \
     CARGO_HOME=/usr/local/cargo \
     PATH=/usr/local/cargo/bin:$PATH
-RUN curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y --default-toolchain 1.85.0 \
+RUN curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y --default-toolchain 1.92.0 \
     && chmod -R a+r /usr/local/rustup /usr/local/cargo
 
 # Install Claude Code CLI (for claude-bridge mode)