Decouple read-only Code/Tooling from Runtime initialization

[AntoineToussaint]

Read-only Code and Tooling calls currently acquire an AgentSession that unconditionally runs Runtime.Load and Runtime.Init. This couples project inspection to toolchain/environment readiness, adds startup latency, and can prevent semantic recovery on malformed projects before the analyzer runs. Make Runtime initialization lazy and concurrency-safe: Code/Tooling must start the production agent without Runtime lifecycle; Build/Test/Lint/Stop initialize Runtime on first use; runtime initialization failures retain the existing typed env-blocked Test response. Verify real GetProjectInfo/GetSemanticIndex against malformed source and preserve runtime behavior. Supports #268 and codefly-dev/mind#369.

[AntoineToussaint]

First attempted proof (not shipped in the semantic PR):\n\n- moved Runtime.Load/Init behind Runtime methods\n- added a distinct attached source root for synthesized services\n- real Gateway JVM/.NET read-only inspection then worked without Runtime.Init\n- however the real Python explicit-formula scenario regressed: its uv process resolved to /opt/homebrew/bin/uv but exec returned ENOENT under the altered environment boundary instead of the expected typed no-tests-executed result\n\nConclusion: lazy Runtime is correct, but the source/process/environment split needs a first-class agent lifecycle contract and full real-agent qualification. The attempted coupling change was removed from #268/#190; no workaround was kept.