feat: simulate network failures, deterministic and probabilistic

[MaxMichel2]

Summary

Closes #88, #95.

Stacked on #127 (PR chain: #123 → #124 → #127 → this) — merge in order.

Adds the ability to make an operation fail instead of returning a response — the class of bugs (timeouts, dropped connections) that's hardest to reproduce on demand during manual testing, and most valuable to have mockable.

What changed

• OperationMockState.Failure(kind: FailureKind): a new sealed-interface variant alongside Network/Mock. Every request to the operation fails the same way until the selection changes — the deterministic case (feat: simulate network failures #88). FailureKind has TIMEOUT and CONNECTION_REFUSED, each mapped in the Ktor plugin to the real exception a Ktor engine throws for the equivalent condition (HttpRequestTimeoutException / a connection-level kotlinx.io.IOException), so an app's existing error handling exercises the same code path against the simulated failure.
• Operation.failureRate (from a new x-devview.failureRate extension field) — the probabilistic case (feat: probabilistic failure-rate injection #95). Deliberately operation-level only, with no spec-wide default (unlike delayMs) — "some percentage of everything fails" is a much blunter tool than "this specific flaky endpoint fails sometimes." Each request to an otherwise-mocked operation independently rolls against the configured rate before serving its response; an operation left on Network passthrough is never affected.
• NetworkMockConfig.random: Random: injectable, defaults to Random.Default, so tests pin the probabilistic roll deterministically instead of relying on real randomness.
• UI: a "Simulate Failure" section in the operation picker page, one row per FailureKind, plus a read-only note showing the configured failure rate when the spec declares one.

Public API (breaking, per your call on 0.2.0 alphas)

• OperationMockState gains a new sealed subtype (Failure) — any exhaustive when an integrator has over it needs a new branch. Updated internally: EndpointCard, EndpointStateChip, NetworkMockOperationSheet's selected-response lookup, ModelUtils' icon/color extensions, and NetworkMockScreen's Mocked/Network list filter (folds Failure into "Mocked", since it's a deliberately-configured non-default state like Mock).
• MockColorScheme gains a new required constructor parameter (failure: StatusColors) — matches Operation.method's precedent in alpha03.
• api.txt regenerated for all three affected modules (devview-networkmock-core, devview-networkmock-ktor, devview-networkmock) via metalavaGenerateSignature.

Tests

• MockConfigRepositoryTest: x-devview.failureRate parses as operation-level with no spec-wide default.
• MockStateRepositoryTest: Failure state round-trips through the real DataStore JSON encode/decode path.
• NetworkMockPluginTest: deterministic Failure(TIMEOUT)/Failure(CONNECTION_REFUSED) throw the right exception type; a fake Random pinned to "always hits"/"always misses" proves the probabilistic roll; the roll is confirmed to not apply when the endpoint state is Network.

Docs updated: networkmock-core.md (new "Simulating failures" section), networkmock-ui.md, networkmock-workflows.md (new workflow), theming.md, and all three module CLAUDE.md files.

Verification

.\gradlew.bat detektFull -Pandroidx.baselineprofile.skipgeneration
.\gradlew.bat cleanTestAndroidHostTest testAndroidHostTest -Pandroidx.baselineprofile.skipgeneration
.\gradlew.bat :konsist:test -Pandroidx.baselineprofile.skipgeneration
.\gradlew.bat :sample:androidApp:assembleDebug -Pandroidx.baselineprofile.skipgeneration
.\gradlew.bat :devview-networkmock:compileAndroidDeviceTest -Pandroidx.baselineprofile.skipgeneration

All green, including a full repo-wide testAndroidHostTest run to confirm no fallout outside the networkmock modules.

🤖 Generated with Claude Code