refactor: architecture improvements for contributor velocity (#198)

* refactor: split large files and consolidate test stubs for contributor velocity

- Extract 7 Database sub-traits (ConversationStore, JobStore, SandboxStore,
  RoutineStore, ToolFailureStore, SettingsStore, WorkspaceStore) with Database
  as a supertrait combining them all
- Split libsql_backend.rs (2769 lines) into src/db/libsql/ directory with
  one file per sub-trait implementation
- Split config.rs (1753 lines) into src/config/ directory with 16 domain files
- Consolidate 3 duplicate test LLM stubs into shared StubLlm in src/testing.rs
- Split server.rs handlers into src/channels/web/handlers/ directory
- Extract main.rs init phases into AppBuilder (src/app.rs)
- Add developer setup script (scripts/dev-setup.sh)

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

* refactor: move heartbeat test from examples/ to tests/

Convert standalone example binary into a proper #[ignore] integration
test, matching the convention of the other integration tests.

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

* style: fix rustfmt formatting for CI

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

* fix: address PR review comments from Copilot

- tunnel.rs: replace .ok().flatten() with ? to propagate env var errors
- secrets.rs: remove misleading "process-wide cache" comment
- database.rs: use uppercase "DATABASE_URL" in error key
- testing.rs: gate harness tests with #[cfg(feature = "libsql")]

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

---------

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

scripts/dev-setup.sh

@@ -0,0 +1,56 @@
+#!/usr/bin/env bash
+# Developer setup script for IronClaw.
+#
+# Gets a fresh checkout ready for development without requiring
+# Docker, PostgreSQL, or any external services.
+#
+# Usage:
+#   ./scripts/dev-setup.sh
+#
+# After running, you can:
+#   cargo check           # default features (postgres + libsql)
+#   cargo test            # default test suite (uses libsql temp DB)
+#   cargo test --all-features         # full test suite
+
+set -euo pipefail
+
+cd "$(dirname "$0")/.."
+
+echo "=== IronClaw Developer Setup ==="
+echo ""
+
+# 1. Check rustup
+if ! command -v rustup &>/dev/null; then
+    echo "ERROR: rustup not found. Install from https://rustup.rs"
+    exit 1
+fi
+echo "[1/5] rustup found: $(rustup --version 2>/dev/null | head -1)"
+
+# 2. Add WASM target (required by build.rs for channel compilation)
+echo "[2/5] Adding wasm32-wasip2 target..."
+rustup target add wasm32-wasip2
+
+# 3. Install wasm-tools (required by build.rs for WASM component model)
+echo "[3/5] Installing wasm-tools..."
+if command -v wasm-tools &>/dev/null; then
+    echo "  wasm-tools already installed: $(wasm-tools --version)"
+else
+    cargo install wasm-tools --locked
+fi
+
+# 4. Verify the project compiles
+echo "[4/5] Running cargo check..."
+cargo check
+
+# 5. Run tests using libsql temp DB (no Docker/external DB needed)
+echo "[5/5] Running tests (no external DB required)..."
+cargo test
+
+echo ""
+echo "=== Setup complete ==="
+echo ""
+echo "Quick start:"
+echo "  cargo run                            # Run with default features"
+echo "  cargo test                           # Test suite (libsql temp DB)"
+echo "  cargo test --all-features            # Full test suite"
+echo "  cargo clippy --all-features          # Lint all code"