feat: stream go test failure summary and drop raw json artifact (#25146)

This follows up on
https://github.com/coder/coder/actions/runs/25684936801/job/75406131184?pr=25139
by replacing the large raw Go test JSON artifact with inline structured
summaries and a compact failures-only artifact.

## What changed

- Added `scripts/gotestsummary`, a streaming Go tool that reads
gotestsum JSON and renders failed tests as Markdown.
- Updated the three Go test jobs to publish per-test `<details>`
sections in the job summary.
- Removed upload of the raw `go-test.json` artifact.
- Added upload of `go-test-failures-*.ndjson` with compact failure
records for deeper inspection.
- Deleted the old bash and `jq` summary script.

## Why

- The previous raw artifact was about 35 MB compressed and 445 MB raw in
the linked run.
- Passing-test output made the artifact noisy and slow to inspect.
- The old summary truncated output to 600 characters.
- The new path keeps streaming, bounded output and writes structured
diagnostics for only final failed tests.

## Validation

- `gofmt -w scripts/gotestsummary`
- `gofmt -l scripts/gotestsummary`
- `go test ./scripts/gotestsummary/...`
- `go vet ./scripts/gotestsummary/...`
- `grep -rn 'go-test-failure-summary.sh' . || true`
- `grep -rn 'go-test-failure-summary.sh\|go-test.json\|go-test-json-'
.claude .agents docs AGENTS.md || true`
- `make lint/agents`
- `make lint/emdash`
- `make lint/markdown`
- `make lint/shellcheck`
- `git diff --check origin/main..HEAD`

> This PR was prepared by Mux working on Mike's behalf.

.github/workflows/ci.yaml

@@ -560,14 +560,21 @@ jobs:
 
       - name: Publish Go test failure summary
         if: failure() && github.actor != 'dependabot[bot]' && runner.os == 'Linux' && !github.event.pull_request.head.repo.fork
-        run: bash scripts/go-test-failure-summary.sh "${RUNNER_TEMP}/go-test.json" >> "$GITHUB_STEP_SUMMARY"
+        run: |
+          go run ./scripts/gotestsummary \
+            --jsonfile "${RUNNER_TEMP}/go-test.json" \
+            --markdown-out - \
+            --failures-out "${RUNNER_TEMP}/go-test-failures.ndjson" \
+            --max-output-bytes 16384 \
+            --max-failures 50 \
+            >> "$GITHUB_STEP_SUMMARY"
 
-      - name: Upload Go test JSON
+      - name: Upload Go test failures
         if: failure() && github.actor != 'dependabot[bot]' && runner.os == 'Linux' && !github.event.pull_request.head.repo.fork
         uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
         with:
-          name: go-test-json-${{ github.job }}-${{ github.sha }}
-          path: ${{ runner.temp }}/go-test.json
+          name: go-test-failures-${{ github.job }}-${{ github.sha }}
+          path: ${{ runner.temp }}/go-test-failures.ndjson
           retention-days: 7
 
       - name: Upload failed test db dumps
@@ -671,14 +678,21 @@ jobs:
 
       - name: Publish Go test failure summary
         if: failure() && github.actor != 'dependabot[bot]' && runner.os == 'Linux' && !github.event.pull_request.head.repo.fork
-        run: bash scripts/go-test-failure-summary.sh "${RUNNER_TEMP}/go-test.json" >> "$GITHUB_STEP_SUMMARY"
+        run: |
+          go run ./scripts/gotestsummary \
+            --jsonfile "${RUNNER_TEMP}/go-test.json" \
+            --markdown-out - \
+            --failures-out "${RUNNER_TEMP}/go-test-failures.ndjson" \
+            --max-output-bytes 16384 \
+            --max-failures 50 \
+            >> "$GITHUB_STEP_SUMMARY"
 
-      - name: Upload Go test JSON
+      - name: Upload Go test failures
         if: failure() && github.actor != 'dependabot[bot]' && runner.os == 'Linux' && !github.event.pull_request.head.repo.fork
         uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
         with:
-          name: go-test-json-${{ github.job }}-${{ github.sha }}
-          path: ${{ runner.temp }}/go-test.json
+          name: go-test-failures-${{ github.job }}-${{ github.sha }}
+          path: ${{ runner.temp }}/go-test-failures.ndjson
           retention-days: 7
 
       - name: Upload Test Cache
@@ -766,14 +780,21 @@ jobs:
 
       - name: Publish Go test failure summary
         if: failure() && github.actor != 'dependabot[bot]' && runner.os == 'Linux' && !github.event.pull_request.head.repo.fork
-        run: bash scripts/go-test-failure-summary.sh "${RUNNER_TEMP}/go-test.json" >> "$GITHUB_STEP_SUMMARY"
+        run: |
+          go run ./scripts/gotestsummary \
+            --jsonfile "${RUNNER_TEMP}/go-test.json" \
+            --markdown-out - \
+            --failures-out "${RUNNER_TEMP}/go-test-failures.ndjson" \
+            --max-output-bytes 16384 \
+            --max-failures 50 \
+            >> "$GITHUB_STEP_SUMMARY"
 
-      - name: Upload Go test JSON
+      - name: Upload Go test failures
         if: failure() && github.actor != 'dependabot[bot]' && runner.os == 'Linux' && !github.event.pull_request.head.repo.fork
         uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
         with:
-          name: go-test-json-${{ github.job }}-${{ github.sha }}
-          path: ${{ runner.temp }}/go-test.json
+          name: go-test-failures-${{ github.job }}-${{ github.sha }}
+          path: ${{ runner.temp }}/go-test-failures.ndjson
           retention-days: 7
 
       - name: Upload Test Cache