Build a verified ARMv7 Grease runtime for phone Cat Food

[isomorphisms]

Build the current pinned Oils/YSH-derived Grease implementation for the physical Android/Termux phone without installing a compiler toolchain on the device.

This keeps Grease as the executable/orchestration language used by IB. It does not substitute ish, POSIX sh, or an unfinished Idriç ARM backend for Grease.

The workflow:

• verifies the exact source/ gitlink used by Grease;
• asks the inherited Oils build to generate the native C++ source bundle from that exact revision;
• cross-builds that bundle with the GitHub runner's Android NDK for armeabi-v7a;
• uses Android API 28 because bionic exposes the POSIX glob/globfree surface required by the current Grease runtime there;
• omits readline for the compact noninteractive phone runtime;
• statically links the C++ runtime, rejects libc++_shared.so, and verifies the ELF machine is ARM;
• packages bin/grease plus its bin/ysh engine and provenance receipts;
• uploads build evidence and, on the branch push, publishes an immutable-by-digest prerelease asset.

Current cloud receipt

• Grease packaging commit: 6015e312ca05dd8103637e3f8bc19927b4e20dba
• Pinned current Grease/Oils source: 8052868773077602266d80bf39aad6998e2da749
• GitHub Actions run: 34530822698 — PASS
• ABI: armeabi-v7a
• Android API floor: 28
• release tag: phone-armv7-6015e312ca05
• archive SHA-256: 70ca729a150d849902d76623977af567f77a5b7e4f1ace4a17dda0e1623a175d

Phone Cat Food now pins this exact archive and digest on its phone branch. Physical-phone execution remains the final acceptance boundary; keep this PR draft until the exact artifact has been installed and exercised there, including a Grease readable-syntax smoke and an actual IB Grease program.