tri devkit: ship the FPGA flow timer and bitwalk in the tri release #1272

The post https://t27.ai/#/blog/the-fpga-flow-layer-by-layer and the page https://t27.ai/#/devkit show tri devkit flow and tri devkit impact. Today these run only on the author's machine: tri devkit is a local script, and bitwalk (L3 FASM → frames, L4 frames → .bit, from t27 specs) is built from the open gHashTag/t27#5609 branch. A reader cannot install either.

Goal: one line installs a tri from the GitHub release that has tri devkit.

• tri devkit flow and tri devkit impact in the Zig tri CLI (src/tri/): time yosys, nextpnr-xilinx, fasm2frames and xc7frames2bit on the reader's own openXC7 build, run the t27 replacements on the same FASM, byte-compare, print the layer table and Amdahl ceilings.
• bitwalk shipped next to tri in the release archives (macOS arm64/amd64, Linux amd64/arm64), built from gHashTag/t27 specs/xilinx7.
• The prjxray-db digest bitwalk --fasm reads, produced without the local Python helper (or shipped per part with the release, with prjxray-db's licence and revision).
• A one-line install in the release notes and in the post, checked on a clean machine.

Until then the post says it is not installable yet and links here.