feat(j5): integrate agent project mutations with Squadron ownership #134

The upstream integration deliberately leaves t3_project_create, t3_project_update, and t3_project_delete out of the agent catalog. The maintainer approved this deferral to keep the merge bounded. Project reads and repository clone remain available; existing human UI controls are unchanged.

Evaluate and implement the smallest policy that lets agents use these upstream operations while keeping Squadron folder references, membership, and thread lifecycle consistent. Updates can change workspaceRoot, scripts and defaults; forced deletion can remove a nonempty project. Preserve upstream permission checks and environment-local authority; do not infer a Squadron home from a project ID.

Acceptance:

• Define the effect of create, workspace changes and forced deletion on referenced Squadrons and their agents before exposing the tools.
• Reuse upstream handlers/services through a small J5 boundary; cover client/tool entry points where the shared behavior changes.
• Test registry/reference consistency, deletion lifecycle, retries, and colliding IDs across environments.
• Add the tools to production discovery and direct-call coverage only after those guarantees hold.

Separate follow-up to the upstream merge; no spawn_agent expansion (tracked in #133).