refactor(model-core): host snapshot fetcher, suggestion parser, and context-limit resolver

Move three pure helpers from src/shared/ into @oh-my-opencode/model-core so the package can stand alone without depending on plugin internals:

- buildModelCapabilitiesSnapshotFromModelsDev + fetchModelCapabilitiesSnapshot (models.dev normalization)
- parseModelSuggestion (cross-provider ProviderModelNotFoundError suggestion extraction)
- resolveActualContextLimit (Anthropic GA 1M context override)

Split provider-model-id-transform into two variants exposed by model-core:

- transformModelForProvider keeps the runtime dash to dot Anthropic rewrite used by the SDK
- transformModelForProviderDisplay preserves hyphenated Anthropic IDs so the installer writes registry-compatible model strings, fixing the ProviderModelNotFoundError fresh installs hit when the dotted form leaks into the config

src/shared/* and src/cli/provider-model-id-transform.ts collapse to re-export shims that point at the new core modules. Stale src/shared/{known-variants,model-capability-aliases,model-capability-guardrails,model-capability-heuristics}.ts re-export files plus the duplicated context-limit-resolver test are removed in favor of the canonical model-core copies.

Tests: bun test packages/model-core src/shared/model-capabilities-cache.test.ts src/cli/provider-model-id-transform.test.ts

src/shared/model-capabilities-cache.test.ts

@@ -6,9 +6,7 @@ import { existsSync, mkdirSync, mkdtempSync, readFileSync, rmSync, writeFileSync
 import { tmpdir } from "node:os"
 import { join } from "node:path"
 import {
-  buildModelCapabilitiesSnapshotFromModelsDev,
   createModelCapabilitiesCacheStore,
-  MODELS_DEV_SOURCE_URL,
 } from "./model-capabilities-cache"
 
 let fakeUserCacheRoot = ""
@@ -28,106 +26,6 @@ describe("model-capabilities-cache", () => {
     testCacheDir = ""
   })
 
-  test("builds a normalized snapshot from provider-keyed models.dev data", () => {
-    //#given
-    const raw = {
-      openai: {
-        models: {
-          "gpt-5.4": {
-            id: "gpt-5.4",
-            family: "gpt",
-            reasoning: true,
-            temperature: false,
-            tool_call: true,
-            modalities: {
-              input: ["text", "image"],
-              output: ["text"],
-            },
-            limit: {
-              context: 1_050_000,
-              output: 128_000,
-            },
-          },
-        },
-      },
-      anthropic: {
-        models: {
-          "claude-sonnet-4-6": {
-            family: "claude-sonnet",
-            reasoning: true,
-            temperature: true,
-            limit: {
-              context: 1_000_000,
-              output: 64_000,
-            },
-          },
-        },
-      },
-    }
-
-    //#when
-    const snapshot = buildModelCapabilitiesSnapshotFromModelsDev(raw)
-
-    //#then
-    expect(snapshot.sourceUrl).toBe(MODELS_DEV_SOURCE_URL)
-    expect(snapshot.models["gpt-5.4"]).toEqual({
-      id: "gpt-5.4",
-      family: "gpt",
-      reasoning: true,
-      temperature: false,
-      toolCall: true,
-      modalities: {
-        input: ["text", "image"],
-        output: ["text"],
-      },
-      limit: {
-        context: 1_050_000,
-        output: 128_000,
-      },
-    })
-    expect(snapshot.models["claude-sonnet-4-6"]).toEqual({
-      id: "claude-sonnet-4-6",
-      family: "claude-sonnet",
-      reasoning: true,
-      temperature: true,
-      limit: {
-        context: 1_000_000,
-        output: 64_000,
-      },
-    })
-  })
-
-  test("merges repeated snapshot entries without materializing empty optional objects", () => {
-    const raw = {
-      openai: {
-        models: {
-          "gpt-5.4": {
-            id: "gpt-5.4",
-            family: "gpt",
-          },
-        },
-      },
-      alias: {
-        models: {
-          "gpt-5.4-preview": {
-            id: "gpt-5.4",
-            reasoning: true,
-          },
-        },
-      },
-    }
-
-    const snapshot = buildModelCapabilitiesSnapshotFromModelsDev(raw)
-
-    expect(snapshot.models["gpt-5.4"]).toEqual({
-      id: "gpt-5.4",
-      family: "gpt",
-      reasoning: true,
-    })
-    expect(snapshot.models["gpt-5.4"]).not.toHaveProperty("modalities")
-    expect(snapshot.models["gpt-5.4"]).not.toHaveProperty("limit")
-  })
-
   test("refresh writes cache and preserves unrelated files in the cache directory", async () => {
     //#given
     const sentinelPath = join(testCacheDir, "keep-me.json")
@@ -135,7 +33,7 @@ describe("model-capabilities-cache", () => {
     mkdirSync(testCacheDir, { recursive: true })
     writeFileSync(sentinelPath, JSON.stringify({ keep: true }))
 
-    const fetchImpl: typeof fetch = async () =>
+    const fetchImpl = async () =>
       new Response(JSON.stringify({
         openai: {
           models: {