feat: LogosCore runs the runtime in a process of its own

[dlipicar]

Part of running the Logos runtime in a process of its own (logos-co/logos-liblogos#229). Stacked on #170 (feat/drop-legacy-mode).

What changes

logos::host::LogosCore runs the runtime in a process of its own by default.

• Config::separateProcess, on by default. start() spawns liblogos' bin/logos_runtime with the host's settings (logos_runtime_spawn) and takes the binding it hands back. capability_module and every module's credential then stay out of the host's process.
• Nothing else changes for callers. Every call already went through core_service over the binding, so lifecycle, queries and consumers keep their signatures.
• Where a setting is refused. In-process, a refused setting still throws from the constructor. With a separate runtime it is refused there, and start() throws with the runtime's reason. So does a spawn that fails, for example with no token authority.
• processModule goes over the runtime's private channel once it has started (logos_runtime_process_module). It is never a core_service call.
• onRuntimeExit(callback) hears of a separate runtime that exits before the host stops it. The destructor stops the runtime, which unloads its modules in order.
• With separateProcess off the runtime runs in the host's process, as before, for tests and single-process deployments.
• The C mirror gains the five logos_runtime_* declarations.

Verification

• checks.tests on macOS: 393/393. The in-process cases now opt out explicitly.
• New cases: a separate runtime is the default; start() spawns with every setting and nothing is configured in the host's process; a failed spawn throws with its reason and cleans nothing up; processModule runs in the runtime; the runtime's exit reaches the host.
• Downstream: Basecamp, the standalone app (logos-co/logos-qt-sdk, logos-co/logos-basecamp, logos-co/logos-standalone-app) on macOS and Linux.

🤖 Generated with Claude Code

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