feat: run lightning at cpu-8 (8 vCPU / 16 GiB) in dax benchmark

[rusenask]

What

Sizes the lightning provider to 8 vCPU / 16 GiB (cpu-8) in the dax benchmark, matching the standardized resource profile introduced in #196.

Why

Lightning was already in the dax matrix but had no resource sizing, so it ran on the SDK default cpu-1 (1 vCPU) while every other provider used 8 vCPU / 16 GiB — making its results incomparable (the same issue #196 fixed for the rest of the matrix).

How

Lightning can't be sized through DAX_RESOURCE_OPTIONS like most providers. The @computesdk/lightning wrapper applies instanceType from the provider factory config and overrides any instanceType passed to sandbox.create():

const params = { ...providerOptions, instanceType: config.instanceType ?? DEFAULT_INSTANCE_TYPE };

So sizing has to happen at createCompute time. This PR:

• Reads LIGHTNING_INSTANCE_TYPE in createCompute (default cpu-1, the SDK default), mirroring how northflank reads its deployment plan from env with a fallback.
• Sets LIGHTNING_INSTANCE_TYPE: cpu-8 in the dax workflow env, scoping the 8 vCPU sizing to the dax benchmark and leaving other modes (e.g. TTI) on the default.
• Documents the mechanism in dax.ts (next to the existing E2B note) and env.example.

Verification

Ran the dax benchmark against lightning.ai with cpu-8:

lightning: 7/7 phases | total 41.93s | prepare 4.37s | clone 2.41s | install 12.91s | typecheck 16.04s (1/1 OK)

The sandbox reports 8 logical CPUs, confirming cpu-8 took effect, and all 7 dax phases complete.

🤖 Generated with Claude Code

[open-cla]

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