ci(fpga): print nextpnr's log when a seed search finds no clean seed

[gHashTag]

Closes #856.

Change

In each of 38 workflows, the seed search's failure branch goes from

[ "$CLEAN" = "0" ] && { echo "::error::no clean seed"; exit 1; }

to

[ "$CLEAN" = "0" ] && { echo "::error::no clean seed"; tail -n 15 /tmp/np_*.log; exit 1; }

This is the idiom ax7203-format-cost.yml already uses. 38 insertions, 38 deletions, nothing else.

How it was applied

A script rewrote the files behind a per-file gate. A file was refused unless:

• exactly one matching line, outside a comment;
• the parsed YAML is unchanged except for that one run: string;
• that string differs from the original by exactly the inserted text, once;
• the new string passes bash -n (with ${{ … }} replaced by a placeholder).

The result was 38 rewritten and 2 refused: format-cost already prints the logs, and build-timing has the phrase only in a comment. A second pass rewrites 0.

Negative controls. Five corrupted rewrites, all refused by the gate: the text inserted twice, an unbalanced quote, the seed loop altered, another step altered, and the exit 1 dropped.

The logs are on the host. All 38 > /tmp/np_*.log redirects are in the runner's shell, not inside a quoted docker … bash -c "…". So a host-side tail can read them (checked by parsing every run: string).

Checks

• actionlint on the 38 files: no findings.
• tools/check_run_syntax.py: 120 of 120 workflows read, 0 steps that do not parse.

Not measured

• What the logs will actually say for ax7203-gf10-sub. It fails on main today (run 37198621522) and on fix(ci): key the chipdb cache on the openXC7 image so it can hit #852 with the bare "no clean seed". A dispatch on this branch is running, and its output will go on ci(fpga): seed searches hide nextpnr's log when every seed fails #856.
• Log volume: with 8 failed seeds this prints up to about 8 × 16 lines. Nobody has asked for less, so it was not trimmed.

🤖 Generated with Claude Code

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