refactor(shared): deduplicate model resolution utility functions

Extract normalizeModel() (3 identical copies) and normalizeModelID()
(2 identical copies) into canonical src/shared/model-normalization.ts.
Delete dead-end duplicate model-name-matcher.ts. Update all consumers.

src/hooks/anthropic-effort/hook.ts

@@ -1,11 +1,7 @@
-import { log } from "../../shared"
+import { log, normalizeModelID } from "../../shared"
 
 const OPUS_4_6_PATTERN = /claude-opus-4[-.]6/i
 
-function normalizeModelID(modelID: string): string {
-  return modelID.replace(/\.(\d+)/g, "-$1")
-}
-
 function isClaudeProvider(providerID: string, modelID: string): boolean {
   if (["anthropic", "google-vertex-anthropic", "opencode"].includes(providerID)) return true
   if (providerID === "github-copilot" && modelID.toLowerCase().includes("claude")) return true

src/hooks/think-mode/switcher.ts

@@ -16,6 +16,8 @@
  * inconsistencies defensively while maintaining backwards compatibility.
  */
 
+import { normalizeModelID } from "../../shared"
+
 /**
  * Extracts provider-specific prefix from model ID (if present).
  * Custom providers may use prefixes for routing (e.g., vertex_ai/, openai/).
@@ -36,24 +38,6 @@ function extractModelPrefix(modelID: string): { prefix: string; base: string } {
   }
 }
 
-/**
- * Normalizes model IDs to use consistent hyphen formatting.
- * GitHub Copilot may use dots (claude-opus-4.6) but our maps use hyphens (claude-opus-4-6).
- * This ensures lookups work regardless of format.
- *
- * @example
- * normalizeModelID("claude-opus-4.6") // "claude-opus-4-6"
- * normalizeModelID("gemini-3.5-pro") // "gemini-3-5-pro"
- * normalizeModelID("gpt-5.2") // "gpt-5-2"
- * normalizeModelID("vertex_ai/claude-opus-4.6") // "vertex_ai/claude-opus-4-6"
- */
-function normalizeModelID(modelID: string): string {
-  // Replace dots with hyphens when followed by a digit
-  // This handles version numbers like 4.5 → 4-5, 5.2 → 5-2
-  return modelID.replace(/\.(\d+)/g, "-$1")
-}
-
-
 
 // Maps model IDs to their "high reasoning" variant (internal convention)
 // For OpenAI models, this signals that reasoning_effort should be set to "high"