Fulfill client runtime tools through callbacks

[chubes4]

Summary

• Routes executor=client / external_executor runtime tool calls through an inline transport callback path before PHP tool execution.
• Emits run-scoped runtime tool request/result events and normalizes fulfilled, failed, or missing client results into normal tool result messages.
• Adds smoke coverage proving a model-called client runtime tool is fulfilled through the callback path and returns to the provider for the follow-up turn.

Scope

This PR is the inline fulfillment foundation for scoped client runtime tools. It does not implement durable pause/resume through Action Scheduler; that should be a follow-up runtime tool broker layer so clients that cannot answer inline can fulfill later and resume the conversation safely.

Refs #2205.
Refs #1485.

Tests

• php -l inc/Engine/AI/conversation-loop.php
• php -l tests/agent-conversation-runner-request-smoke.php
• php tests/agent-conversation-runner-request-smoke.php
• php tests/tool-source-registry-smoke.php
• git diff --check

AI assistance

• AI assistance: Yes
• Tool(s): OpenCode (GPT-5.5)
• Used for: Implemented the runtime tool callback fulfillment path and smoke coverage; Chris remains responsible for review and merge.

[homeboy-ci]

Homeboy Results — data-machine

Audit

✅ audit — passed

• requested_detectors — 9 finding(s)
• intra-method-duplication — 7 finding(s)
• dead_code — 4 finding(s)
• Directives — 1 finding(s)
• Retention — 1 finding(s)
• Total: 22 finding(s)

Deep dive: homeboy audit data-machine --changed-since 3194452

Artifacts and drill-down

• CI results artifact: homeboy-ci-results-data-machine-audit-quality-Linux-node24 contains immediate command JSON for this action invocation.
• Observation artifact: homeboy-observations-data-machine-audit-quality-Linux-node24 contains exported Homeboy run history for deeper queries.
• Drill-down: download the observation artifact, then run homeboy runs import <dir>, homeboy runs list, and homeboy runs findings <run-id>.
• Artifacts are attached to the workflow run: https://github.com/Extra-Chill/data-machine/actions/runs/26337390972

Tooling versions

• Homeboy CLI: homeboy 0.197.2+43f80721
• Extension: wordpress from https://github.com/Extra-Chill/homeboy-extensions
• Extension revision: dd23ee80
• Action: unknown@unknown