Bump bundled shiv to v0.3.6

[junior-ricon]

Summary

• bump vfox-shiv's reproducible bootstrap from shiv v0.3.2 to v0.3.6;
• update bootstrap test expectations and the delegated-install readiness fixture;
• regenerate README so the badge, architecture diagram, and environment reference show the active bootstrap.

This propagates the install-local task-map ownership fix released in KnickKnackLabs/shiv v0.3.6. Without this bump, normal shiv:* installs would continue generating package shims through the older bundled shiv.

Validation

• VFOX_SHIV_PATH=/tmp/junior.d/vfox-shiv-v036-test/bootstrap-shiv mise run test — 82/82 passed;
• isolated bootstrap resolved signed shiv v0.3.6 at 4ad99d89edfe10b13bbfa127a4c7b0009cb60562;
• mise exec -- readme build --check;
• git diff --check;
• fold git pre-commit and git pre-push completed (pre-push warned only for the new branch lacking an upstream and historical GitHub merge signatures).

Release continuation

After approval and merge, Junior retains closure ownership: release signed vfox-shiv v0.2.3, then smoke a normal home-style shiv:emails@0.7 consumer against a conflicting stale global task map.

Validation caveat

This repo has no configured aggregate codebase lint task or [_.codebase] rule set. The attempted ambient aggregate command failed as unavailable and is not counted as passing validation.

[junior-ricon]

Or reviewed exact head 3f7700545f86ffe168986946a02f3850030c853a live with Junior and approved merge. Ubuntu and macOS CI are green at that head. Junior retains merge, release, and consumer-smoke ownership.