feat(#2093): migrate Kilo onto EoS imperative adapter + hook-bus/model/MCP/dispatch upgrades (ADR-1239)

Fold remaining isKilo logic branches into descriptor-driven reads:
finishPermissionWriter (uninstall cleanup), skipSharedHooksInstall (hooks
copy), and a skills converter-name registry (the artifactLayout.converter
field is now load-bearing, not decorative). frontmatterDialect stays the
documented dispatch key for frontmatter (no descriptor field for it). Dead
isKilo destructure bindings removed. Byte-identical golden parity for all 16
runtimes (opencode, which shares kilo's combined-family path, verified clean).

UPGRADE 1 (hook bus): install .kilo/plugins/gsd-core.js native plugin +
extensionEvents:"kilo" + EXTENSION_EVENT_SURFACES.kilo (OpenCode-fork bus).
UPGRADE 2 (active model): populate runtimeTierDefaults.kilo + thread
modelOverride through convertClaudeToKiloFrontmatter — model no longer stripped
from agents. UPGRADE 3 (MCP): document the gsd-core MCP companion under kilo's
mcp config key. UPGRADE 4 (named dispatch): agents/*.md mode:subagent roster is
the Task-tool dispatch surface (tested); subagentToolkit stays 'undocumented'
per AC so dispatch degrades to 'degraded' by design.

Model-catalog single-source edit ripples the shared model-catalog.json hash
into all 16 golden fixtures (expected). Inline defect fixes (no-defer): stale-
bake-guard resolveAgentDir 'agent'->'agents' (was a silent no-op for opencode/
codex), hardcoded 'Removed OpenCode plugin' uninstall log -> generic, and the
connect-gsd-mcp-server.md OpenCode mcpServers->mcp doc error.

Tests: kilo-imperative-reference (adapter/axes/fail-closed/degradation/
hostBehaviors + widened isKilo source-grep across 4 modules) + kilo-upgrades
(plugin parity+load, model-override converter, agents dispatch surface, MCP
doc). Matrix + how-to + config docs updated; changeset added.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/runtime-artifact-layout.cts

@@ -77,6 +77,12 @@ interface ArtifactKind {
    *  specifies one (e.g. codex skills → $HOME/.agents). Undefined means the
    *  kind installs under the runtime's normal configDir. */
   home?: string;
+  /** Name of the converter function in Runtime Artifact Conversion exports, as
+   *  declared on the descriptor's `converter` field. Only populated for the
+   *  `skills` kind today — lets bespoke callers (e.g. the OpenCode-family
+   *  combined installer, ADR-1239 / #2093) look up the descriptor-declared
+   *  converter by name instead of re-deriving it from a runtime === check. */
+  converter?: string;
 }
 
 interface Layout {
@@ -323,6 +329,7 @@ function skillsKind(
     kind: 'skills',
     destSubpath,
     prefix,
+    converter: converterName,
     stage: (resolved) => {
       const realConverter = conversionExports[converterName] as (content: string, skillName: string, runtime: string, cmdNames: string[], isGlobal: boolean) => string;
       // Compute cmdNames once per stage call for performance (#3583).