feat: ship G5 custom agent apps

[miter37]

What changed

• Ship manifest-backed Custom Agent Apps across CLI, GUI, Jobs, and Schedules.
• Harden Agent App testing, hidden-field preservation, shell-free argv rendering, model discovery, and environment allowlisting.
• Unify per-Agent Full Access Mode across GUI, CLI, daemon API, and built-in adapters.
• Add safe real Working folder edits with verified artifact copies and conflict protection.
• Add manual non-interrupting progress checks recorded in the GUI Logs tab.
• Improve health reporting, Answer rendering, task navigation, search, scheduling actions, and Windows subprocess behavior.

Root causes fixed

• GUI edits could overwrite manifest fields that were not exposed by the wizard.
• Pre-save testing persisted ghost Agent Apps and stale passing tests remained saveable.
• Requested real-directory work was constrained to Relay artifacts instead of being applied to the requested folder.
• Running tasks exposed raw logs but no concise, non-interrupting diagnostic snapshot.

Validation

• ruff format --check .
• ruff check .
• python -m unittest discover -s tests — 247 passed, 1 environment-dependent skip
• python build_release.py
• python relay.pyz version — Relay 1.1.0

This PR remains draft as the integration record for the G5 branch; tag v1.1.0 points to the completed release commit.