feat(coder): add model resolution core + multi-batch matcher

Model resolution (from oh-my-openagent/model-core): 6-step priority
resolution pipeline (UI select -> user config -> category default ->
user fallback -> policy chain -> system default), provider fallback
chains, fuzzy model matching, error classification, provider-specific
model ID transforms. 14 files, zero runtime deps.

Multi-batch matcher (from boocontext-audit): 6 batch types
(Observational, Actionable, PreviouslyApplied, Disambiguation,
ResponseAnalysis, LowCriticality) for behavioral guideline evaluation.
RelationalResolver with iterative convergence (DEPENDS_ON,
PRIORITIZES, ENTAILS, TAG_ALL, TAG_PRIORITIZES). SchematicGenerator
abstract class with retry and execution plans. 4 files.

apps/coder/src/services/model-resolution/fallback-model-object.ts

@@ -0,0 +1,9 @@
+export type FallbackModelObject = {
+  readonly model: string
+  readonly variant?: string
+  readonly reasoningEffort?: "none" | "minimal" | "low" | "medium" | "high" | "xhigh" | "max"
+  readonly temperature?: number
+  readonly top_p?: number
+  readonly maxTokens?: number
+  readonly thinking?: { readonly type: "enabled" | "disabled"; readonly budgetTokens?: number }
+}