Configurable per-tool build/test commands + opt-in full-suite go-test runner

[DatScreamer]

Configurable per-tool build/test commands + opt-in full-suite go-test runner

Branch: feat/test-runner-commands (fork: DatScreamer/interlinked-cli)
Design doc: docs/interlinked-test-runners-plan.md (in the branch)

Problem

Every tool runner hard-codes its argv (go build ./..., golangci-lint run ...), there is no
way to override a command via config, and there is no full-suite test tool. A project whose
dev server rebuilds with Go build tags (e.g. -tags 'dev devaccounts') cannot make Interlinked
run that exact command, so its checks compile into a separate Go build cache — measured
~30–84 s cold vs ~6–21 s warm on the motivating Go workspace.

Changes on the branch

1. New two-tier config — .interlinked/tool-commands.json (committed) +
   .interlinked/tool-commands.local.json (gitignored), keyed by check/config names
   (go_build, go_test, golangci_lint, …). A full command array wins; otherwise
   base_args replace the runner's default scope (./...) so Go flag ordering stays correct.
   Trust split mirrors merge.ts: the committed team tier may set base_args +
   timeout_ms (flags for a fixed binary / a bounded cap); command/env stay
   personal-tier (interlinked doctor reports violations). No shell interpolation.
2. Runners honor the override — go-build, golangci-lint, and the new go-test tool
   spawn the configured argv, with sync + async variants (src/harness/check-engine/).
3. New go-test catalog tool — project-wide, opt-in (auto-runs only when the project
   configures go_test, or on explicit --only go-test / --tools go-test /
   verify --only go-test), with generic-fallback + Go test parsers emitting [proven]
   per-test findings. Wired into check --only/--tools/--report, TOOL_IDS, and the
   ALL_TOOL_IDS drift guard.
4. affected_tests carries the tags — PostToolUse on a .go edit runs
   go test <tags> -count=1 ./<pkg>, replacing the full-suite ./... scope with the touched
   package (src/harness/quality-checks/).
5. Skills + docs updated (interlinked-verify, interlinked-setup, router; design doc).

Acceptance (isolated GOCACHE, 2026-09-03, re-confirmed after rebase)

Measurement	Command	Cache state	Wall
Before (stock install)	check --only go-build	untagged, no shared cache	8.7 s
After (branch)	check --only go-build	tagged, dev-warmed reuse	6.0–6.8 s (clean)
After (branch)	check --only go-test	tagged, dev-warmed reuse	21–26 s (per-test findings)
Reference	go build -tags 'dev devaccounts' ./...	fresh (no reuse)	29.3 s
Reference	go test -tags 'dev devaccounts' ./...	fresh (no reuse)	84.4 s

The after-runs hug the warmed-tagged-cache baseline (direct warm repeats 5.5 s build / 23 s
suite), proving the tagged command reuses the dev cache instead of recompiling per surface.

Known v1 gaps (deferred in the plan doc)

• verify --json has no per-runner go-test section yet (fixed-shape schema).
• Coverage-gate resolver wiring (js/ts/python only).
• PostToolUse honors the config after interlinked harness restart in existing repos.