arniwesth/mot 26 csp initial research

[arniwesth]

PR: CSP initial research

Summary

Base branch: arniwesth/mot-25-code-graph-poc.

This branch adds CSP-core feasibility research grounded with the existing code-graph tooling from the
base branch. A run_tool_select implementation spike was attempted and then reverted; the retained
outcome is research, smokes, diagrams, handoff docs, and a direction note recommending a
phase-oriented AILANG core over CSP-first architecture on AILANG v0.26.0.

Changes

• Add .agent/projects/003_CSP_core_refactor/ with feasibility research, ADR, implementation plans,
  handoff docs, and architecture diagrams for a possible CSP tool-phase refactor.
• Add substrate smokes proving std/stream behavior: handler-side Net/stubbed AI,
  source-name routing, process exit-code surfacing, and raw asyncExecProcess not streaming stderr.
• Document the reverted run_tool_select spike and why it only produced a CSP-shaped seam rather
  than a true CSP tool phase.
• Add NOTE-why-not-csp-now.md, documenting why CSP is not the right primary core architecture on
  AILANG v0.26.0 and recommending a phase-oriented core with strict transcript boundaries.
• Add a session summary for the implementation/revert/architecture decision.

Verification

• ailang check src/core/agent_loop_v2.ail
• ailang check src/core/tool_runtime.ail
• ailang check src/core/types.ail
• Production scan confirmed no remaining run_tool_select / wrapper / parallel_safe references in
  src or scripts after the revert.