[derechopiano]

Adds an opt-in workbook-project role for the desktop portion of storytold/gridcraft#1566, building on craft-python 0.3.0.

The ordinary manifest and its Run Script, Console, Run File, PY.EVAL, helpers and WordCraft/DeckCraft behavior stay on their existing path. main.py --workbook-macros uses the existing App/Channel with a small adapter; no second plugin dispatcher or transport is introduced.

• plugin-macros.json has a separate provider identity, no duplicate functions/ribbon commands, and opts out of VBA recording and ribbon callbacks.
• Supports inert AST discovery and editing of workbook-owned modules through the shared macros/* methods. The host owns persistence, trust, editing UI and the workbook transaction.
• Prepares PEP 723 environments with uv and reuses a worker for the same document/source; changes, failure or 60 idle seconds release it. Startup/execution have absolute deadlines and bounded messages/diagnostics.
• Preparation is offline unless the host supplies explicit session/metadata-bound approval. Source builds remain disabled. Worker process-tree ownership is lifecycle management, not an OS sandbox.

Host dependency: sirmmo/gridcraft#4, which requires the proposed pythonProjects/engineCommands capabilities on top of storytold/gridcraft#1123. An unmodified host refuses the manifest. This is separate from Python-in-cells (#469); form controls, Pyodide and rich editor/output work remain later phases of #1566.

Validation:

• Full python -m unittest discover -s tests -v: 68 tests passed, including upstream scripts/console/functions, GridCraft/WordCraft/DeckCraft behavior and the new runtime/adapter checks.
• Compile, JSON/version consistency and the complete Linux Python 3.8/3.12 matrix passed: fork CI. Each platform ran 71 tests: 68 passed, with three lifetime checks applicable only to the other platform.
• Real native GridCraft/uv integration passed: discovery, editing, warm reuse, literal writes, one-step undo, error/Stop rollback and ordinary PY.TWICE recalculation during a macro.
• Native Windows and Linux descendant cleanup passed, including forced cancellation, normal worker exit with descendants holding pipes, and provider-crash cleanup. POSIX ownership uses an idle pipe-lifetime supervisor; Windows retains Job Objects. Native FreeBSD execution remains unverified.