Closes the Apertus rollout (APERTUS_ROLLOUT.md) at 3-of-3 PRs
(plan #91, routing #92, chat-template docs #93, tool calling
#94). Drops the optional PR 4 (rebuild kapertus-cli) — the
unified skainet-cli already covers Apertus end-to-end after #92,
and the workspace direction (per `81f3506` deleting kqwen / kvoxtral
/ kapertus CLIs) is consolidation rather than per-model binaries.

Also lands the deprecated-runtime cleanup that the rollout
deferred. After PR 1 made `OptimizedLLMRuntime + apertusNetwork()`
the canonical path, the hand-coded `ApertusRuntime` and its
quantized variant served no production callers — both were
flagged @deprecated in #92's wake. Removing them now rather than
maintaining stale code through a separate deprecation cycle.

Deleted:

- llm-inference/apertus/.../ApertusRuntime.kt — hand-coded
  decoder runtime. Replaced by OptimizedLLMRuntime + apertusNetwork()
  per #92.
- llm-inference/apertus/.../ApertusQuantizedRuntime.kt — lazy-dequant
  variant. Same canonical replacement path; QuantPolicy.NATIVE_OPTIMIZED
  through the unified loader covers the same memory profile.
- llm-inference/apertus/.../ApertusAttentionBackend.kt — interface
  used only by the two deleted runtimes.
- llm-inference/apertus/.../ApertusCpuAttentionBackend.kt —
  implementation, only used by the two deleted runtimes.
- llm-inference/apertus/.../ApertusRuntimeSmokeTest.kt — exercised
  the deleted ApertusRuntime.
- llm-inference/apertus/.../ApertusQuantizedRuntimeSmokeTest.kt —
  exercised the deleted ApertusQuantizedRuntime.

Extracted (kept):

- llm-inference/apertus/.../ApertusXIELU.kt (new) — `xielu()` and
  `softplus()` reference activation helpers were public functions
  in ApertusRuntime.kt and are still useful as a numerical
  reference (ApertusXIELUTest validates the math, and future
  xIELU implementations can point at this file as the golden
  reference). Pulled out as a standalone activation module so the
  test keeps compiling after ApertusRuntime is gone.

Untouched (still on the production path):

- ApertusNetworkDef.kt — the apertusNetwork() DSL with xIELU op,
  QK-Norm, ungated FFN.
- ApertusNetworkLoader.kt — module-build entry point.
- ApertusWeightLoader.kt + ApertusSafeTensorsLoader.kt — GGUF +
  SafeTensors ingestion. Still used by both ApertusNetworkLoader
  and (in transition) ApertusIngestion's loadQuantized* methods.
- ApertusRuntimeWeights.kt — data classes (ApertusModelMetadata,
  ApertusLayerWeights, ApertusXIELUParams). Used by the network
  path.
- ApertusIngestion.kt (kapertus runtime) — thin facade. Its
  loadQuantized* methods reference ApertusQuantizedRuntimeWeights,
  which lives in the (still-extant) ApertusWeightLoader codepath.
  Verified compiles cleanly after this PR.

Stale code-comment references to "ApertusRuntime" remain in
OptimizedLLMRuntime.kt and llm-core's OutputEquivalenceTest.kt
kdocs — they describe the migration history. Not load-bearing;
left for a future docs sweep.

APERTUS_ROLLOUT.md rewritten as a closure document (status:
complete, summary of the four merged PRs, what was dropped from
PR 4, post-cleanup test footprint).

Verification:

- `:llm-inference:apertus:jvmTest` — 12/12 (ConfigParser 6, XIELU 6).
- `:llm-agent:jvmTest --tests '*Apertus*'` — 21/21 (ChatTemplate 10,
  ParserStrategy 11).
- `:llm-runtime:kapertus:compileKotlinJvm`, `:llm-apps:skainet-cli:compileKotlin`,
  `:llm-core:compileTestKotlinJvm` — all green after the deletes.

Total Apertus test footprint after this commit: 33 tests, all green.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>