feat: add stateful/sequential mocks

[MaxMichel2]

Summary

Closes #96.

Stacked on #128 (PR chain: #123 → #124 → #127 → #128 → this) — merge in order.

Adds sequential/stateful mocks: an operation can advance through an ordered list of responses one step per matched request, sticking on the last step once exhausted. Fills the most common manual-testing gap static mocks can't — polling flows (order status, upload progress, async job completion) where the interesting behavior is the transition across repeated calls.

Design deviation from the issue's proposed shape

The issue suggested persisting the sequence position as a separate DataStore counter, keyed by OperationKey, alongside the existing Sequence state. I went with a simpler design: currentIndex lives inside OperationMockState.Sequence itself (matching the issue's own alternate suggestion, Sequence(responses, currentIndex)), not a second persisted key.

This is strictly simpler and gets the reset requirement for free: MockStateRepository.resetKnownOperationsToNetwork() and NetworkMockState.resetAllToNetwork() already replace the entire OperationMockState value with Network — with position embedded in the same object, it's discarded automatically. A separate counter key would need explicit clearing in both reset paths, which is exactly the trap the issue itself calls out.

What changed

• OperationMockState.Sequence(responses: List<Mock>, currentIndex: Int = 0): a new sealed-interface variant. currentResponse: Mock? safely indexes the current step.
• NetworkMockPlugin: a new Sequence branch — serves the current step, then persists the advanced (exhaustion-clamped) index via stateRepository.setOperationMockState before returning. Shares response-loading with the Mock branch via a new buildMockCall helper (reduces duplication rather than copy-pasting the try/catch). The x-devview.failureRate probabilistic roll from feat: probabilistic failure-rate injection #95 applies to Sequence the same way it does to Mock.
• UI: a "SEQUENCE" section in the operation picker page. Building a sequence is a page-level mode, not a new icon on every response row — "Build a Sequence" changes what tapping a response row does (append to the in-progress list instead of selecting immediately); "Save Sequence" commits (≥2 steps required), "Cancel" discards. An active sequence shows its current step ("200 - default (2/3)") and offers "Reset Position".
• Deliberate v1 scope cut: reordering is by clearing and rebuilding, not drag handles. A full reorder UI is a reasonable follow-up if users actually build sequences in the wrong order often enough to want it — not something to build speculatively now.
• NetworkMockViewModel gains setOperationSequenceState(key, responses) and resetOperationSequencePosition(key).

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

OperationMockState gains another sealed subtype — the same exhaustive-when sites touched for Failure in #128 (EndpointCard, EndpointStateChip, the operation sheet's selected-response lookup, ModelUtils' icon/color extensions, NetworkMockScreen's Mocked/Network filter) needed a Sequence branch too (folded into "Mocked", same reasoning as Failure). api.txt regenerated for devview-networkmock-core and devview-networkmock.

Tests

• MockStateRepositoryTest: Sequence round-trips through the real DataStore JSON path with its position intact; resetting to Network discards a previous sequence position.
• NetworkMockPluginTest: a sequence advances across successive requests and sticks on the last step once exhausted (via a small mutableStateRepositoryMock backed by a real MutableStateFlow, so the plugin's own write-then-reread round-trips like it would against real DataStore); the probabilistic failure roll applies to Sequence states too.

Docs: networkmock-workflows.md (new workflow), networkmock-core.md (DataStore schema entry).

Verification

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

All green (combined run, including a full repo-wide testAndroidHostTest).

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