hive: Support supplying a custom Lifecycle via Options

[KR-Ravindra]

Problem

hive.NewWithOptions always constructs a cell.DefaultLifecycle, so an application embedding hive cannot supply its own cell.Lifecycle (nested lifecycles, hook instrumentation, test harnesses) even though cell.Lifecycle is an exported interface and DefaultLifecycle is exported for that purpose.

Root cause

hive.go:135 (NewWithOptions) hard-codes lifecycle: &cell.DefaultLifecycle{LogThreshold: opts.LogThreshold} and Options has no way to override it.

Fix

Add an optional Lifecycle cell.Lifecycle field to hive.Options, as proposed in the issue. When set, the hive provides it to the cells and drives Start/Stop through it; when nil, a DefaultLifecycle with the configured LogThreshold is created as before, so existing callers are unaffected. cell.Module already passes non-DefaultLifecycle implementations through unchanged.

How tested

Added TestCustomLifecycle (a wrapper embedding *cell.DefaultLifecycle that counts Append/Start/Stop, passed via opts.Lifecycle, asserting it is the lifecycle injected into cells and that each counter is 1 after h.Start/h.Stop) and TestDefaultLifecycle (nil opts.Lifecycle still yields a *cell.DefaultLifecycle carrying opts.LogThreshold).

Before the fix:

./hive_test.go:729:7: opts.Lifecycle undefined (type hive.Options has no field or method Lifecycle)
FAIL	github.com/cilium/hive [build failed]

After the fix:

--- PASS: TestCustomLifecycle (0.00s)
--- PASS: TestDefaultLifecycle (0.00s)
ok  	github.com/cilium/hive	0.016s

go build ./..., go vet ./..., gofmt -l . and go test ./... (plus -race on the root package) pass.

Links

• Fixes support custom lifecycle implementation #39

This change was prepared with an AI agent operated by KR-Ravindra, who reviewed and tested it.