test: migrate to zekr CLI test runner

[brnrdog]

Summary

Installs zekr@2.1.0-beta.2 and refactors both packages' tests to run through zekr's new zekr CLI instead of hand-written Runner entrypoints.

The CLI discovers every *.test.res file and runs each one in its own process. Suites created with Suite.make register themselves with zekr automatically, so the explicit Runner.runSuites calls and the aggregating RunTests.res are no longer needed.

beta.2's harness loads the Runner module compiled with the same suffix as each test file, so both share one Registry instance. That means the CLI works with this repo's existing .res.mjs build — no packaging/suffix changes required.

Changes

• Install zekr@2.1.0-beta.2 (root dev dependency).
• Rename test files to the *.test.res convention the CLI matches:
  • SignalTests.res → Signal.test.res
  • ComputedTests.res → Computed.test.res
  • EffectTests.res → Effect.test.res
  • SignalsReact_test.res → SignalsReactHooks.test.res (the react package has no namespace, so a SignalsReact.test.res module name would collide with src/SignalsReact.res).
• Remove RunTests.res and the explicit Runner.runSuites(...) call from the react tests — suites now auto-register.
• Update test scripts in both packages to rescript && zekr --dir tests.
• Refresh the CONTRIBUTING testing guide for the new zekr API and *.test.res convention.

No changes to the published build output, rescript.json suffix, main/module, or benchmark scripts.

Verification

npm test (clean build) passes:

• rescript-signals: 3 files — Signal (18), Computed (19), Effect (15)
• rescript-signals-react: 1 file — 17 hook/edge-case tests

[github-actions]

ReScript Signals benchmark: PR vs main

Compared implementations:

• ReScript Signals (main)
• ReScript Signals (PR)

Overall:

Version	Total ms	Avg ms/test
ReScript Signals (main)	5531.38	276.57
ReScript Signals (PR)	5695.27	284.76
Delta (ReScript Signals (PR) - ReScript Signals (main))	163.89	2.96%

Per-test delta (lower is better):

Test	Main ms	PR ms	Diff ms	Diff %
2-10x5 - lazy80%	530.33	526.84	-3.49	-0.66%
25-1000x5	1026.53	1048.34	21.81	2.12%
3-5x500	224.41	209.97	-14.44	-6.43%
4-1000x12 - dyn5%	753.69	898.15	144.45	19.17%
6-100x15 - dyn50%	447.58	420.19	-27.40	-6.12%
6-10x10 - dyn25% - lazy80%	290.48	273.39	-17.09	-5.88%
avoidablePropagation	308.25	306.24	-2.01	-0.65%
broadPropagation	225.04	225.28	0.24	0.11%
cellx1000	18.30	16.52	-1.78	-9.72%
cellx2500	86.93	73.46	-13.46	-15.49%
createComputations	265.27	322.98	57.71	21.76%
createSignals	3.24	2.87	-0.37	-11.55%
deepPropagation	91.85	85.90	-5.95	-6.48%
diamond	182.30	177.61	-4.69	-2.57%
molBench	45.01	44.91	-0.10	-0.21%
mux	256.48	251.58	-4.90	-1.91%
repeatedObservers	41.96	38.85	-3.10	-7.40%
triangle	58.28	56.25	-2.03	-3.48%
unstable	63.53	58.74	-4.80	-7.55%
updateSignals	611.93	657.21	45.28	7.40%

Note: single-machine run in CI. Numbers can vary with runner load and Node/V8 version.

[github-actions]

Reactivity benchmark: PR vs top frameworks

Compared implementations:

• Alien Signals
• Preact Signals
• SolidJS
• Svelte v5
• Vue
• ReScript Signals (PR)

Overall ranking (lower total ms is better):

Rank	Framework	Total ms	Avg ms/test
1	Preact Signals	3879.69	193.98
2	Alien Signals	4006.66	200.33
3	ReScript Signals (PR)	5599.33	279.97
4	Vue	5985.58	299.28
5	Svelte v5	8628.99	431.45
6	SolidJS	10567.00	528.35

Per-test runtime (ms):

Framework	2-10x5 - lazy80%	25-1000x5	3-5x500	4-1000x12 - dyn5%	6-100x15 - dyn50%	6-10x10 - dyn25% - lazy80%	avoidablePropagation	broadPropagation	cellx1000	cellx2500	createComputations	createSignals	deepPropagation	diamond	molBench	mux	repeatedObservers	triangle	unstable	updateSignals
Preact Signals	387.61	728.00	188.25	614.42	325.80	230.44	107.33	198.17	9.37	24.99	86.91	1.96	73.84	137.18	32.05	159.29	19.82	42.92	35.49	475.83
Alien Signals	341.63	842.76	198.53	686.87	317.13	235.21	85.91	189.28	8.52	21.18	82.00	2.58	61.95	131.17	32.15	173.98	32.90	39.86	48.97	474.08
ReScript Signals (PR)	537.78	930.00	199.32	880.87	424.61	280.77	319.24	229.66	13.25	41.01	324.15	2.37	106.61	180.32	44.82	291.20	38.23	52.03	58.38	644.74
Vue	574.61	1107.23	286.74	960.16	483.79	361.33	232.95	300.33	22.06	61.83	135.74	2.80	114.18	200.50	69.93	256.67	28.72	64.10	53.00	668.91
Svelte v5	1098.85	1274.02	309.13	1191.97	467.89	395.15	538.83	472.21	14.22	41.38	149.40	1.94	168.65	437.29	34.48	272.81	74.88	130.57	116.15	1439.15
SolidJS	2279.62	1559.04	487.83	1307.13	740.23	748.54	337.12	525.32	20.07	55.58	149.40	4.10	183.31	363.73	39.66	291.86	94.68	126.51	131.54	1121.72

Note: single-machine run in CI. Numbers can vary with runner load and Node/V8 version.

[brnrdog]

Testing the scan-and-run feature from brnrdog/zekr#28