Add an 'spk config' command

[jrray]

Adds spk config, mirroring the existing spfs config command.

It prints the effective spk configuration — after the system file, the user
file, and environment variable overrides have all been merged — as
pretty-printed json. Today there is no way to check what spk actually resolved
its settings to other than inferring it from behavior.

$ spk config
{
  "sentry": { ... },
  "solver": {
    "check_impossible_initial": false,
    ...
  },
  ...
}

Placement

The command lives in spk-cli-group4 alongside the other small informational
commands (version, lint, search, view).

That crate turns out to sit on the tail of the build's critical path —
spk-cli-group2 rmeta → spk-cli-group4 → spk link — with nothing else
gating the final link, so the placement was measured rather than assumed:

	baseline	with spk config
from-scratch cargo build -p spk	101.1s	94.7s
spk-cli-group4 unit	5.9s	5.7s

Since that spread is all noise, the crate was isolated (deps warm,
cargo clean -p spk-cli-group4, CARGO_INCREMENTAL=0, 3 reps each):
baseline mean 6087ms vs. 6055ms with the change — −32ms against a ±250ms
run-to-run spread, i.e. unmeasurable.

That matches the structure: the new module is 30 lines with no generics or
macro expansion, and the spk-config dependency added to group4's
Cargo.toml is a new direct edge to a crate that was already present
transitively and finishes ~58s before group4 starts — it adds no node to the
graph and lengthens no path.

Worth knowing for later, though: anything heavier landing in group4 goes
straight onto the critical path's tail.

Also

• Documents both spfs config and spk config in docs/admin/config.md.

🤖 Generated with Claude Code

https://claude.ai/code/session_01XsbWihJL8svBWeeKHNL2j9

[jrray]

I noticed an LLM looking for a spk config command while working on something and figured we might as well have one.

[codecov]

Codecov Report

❌ Patch coverage is 0% with 6 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
crates/spk-cli/group4/src/cmd_config.rs	0.00%	5 Missing ⚠️
crates/spk/src/cli.rs	0.00%	1 Missing ⚠️

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