chore(config): retire unread keys [dynamic], [evidence], [variants], [models] patcher

Nothing in src reads config.dynamic, config.evidence or config.variants, and
[models] patcher was only echoed into harness.json. They now go through the
existing RETIRED_KEYS mechanism and fail with RetiredConfigError naming why
("retired 2026-10-02 because nothing ever read it: ..."); RETIRED_KEYS now
carries the full reason per key so the HarnessX entries keep their wording.

- DynamicConfig, EvidenceConfig, VariantsConfig and their loaders removed;
  ModelConfig.patcher removed. resolved_config.json loses those sections.
- harness.json keeps its shape: model_roles.patcher is always null.
- RELEASE_NOTES "Unreleased" lists the keys and the output shape change.
- Delete .opencode/skills/openultrasast-kiro-impl: it pointed agents at the
  retired openrouter-sast-harness tasks.

Co-Authored-By: Claude Opus 5.5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01EmM1j46qgKMh3zqD1QMwEo

src/openultrasast/harness.py

@@ -181,7 +181,7 @@ def write_harness_config(
             "ranker": config.models.ranker,
             "hunter": config.models.hunter,
             "verifier": None,  # schema kept byte for byte; LLM verification runs on the plane
-            "patcher": config.models.patcher,
+            "patcher": None,  # schema kept; `[models] patcher` was retired 2026-10-02 (never read)
         },
         processor_versions={processor.spec.name: processor.spec.version for processor in processors},
         prompt_hashes={name: _hash_text(prompt) for name, prompt in sorted(prompts.items())},