fix(ralph-loop): detect promise tags in tool_result parts for ulw verification

Oracle's <promise>VERIFIED</promise> arrives as a tool_result part from the
task() tool call, not as a text part. Both detectCompletionInSessionMessages
and collectAssistantText only scanned type=text parts, missing the
verification signal entirely. This caused ulw loops to fail verification
even when Oracle successfully emitted VERIFIED.

Include tool_result parts in promise detection alongside text parts.
Exclude tool_use parts to avoid false positives from instructional text.

src/hooks/think-mode/switcher.test.ts

@@ -53,22 +53,6 @@ describe("think-mode switcher", () => {
         expect(variant).toBe("gpt-5-4-high")
       })
 
-      it("should handle gpt-5.4-mini model", () => {
-        // given a GPT-5.4-mini model ID
-        const variant = getHighVariant("gpt-5.4-mini")
-
-        // then should return high variant
-        expect(variant).toBe("gpt-5-4-mini-high")
-      })
-
-      it("should handle gpt-5.4-nano model", () => {
-        // given a GPT-5.4-nano model ID
-        const variant = getHighVariant("gpt-5.4-nano")
-
-        // then should return high variant
-        expect(variant).toBe("gpt-5-4-nano-high")
-      })
-
       it("should handle dots in GPT-5.1 codex variants", () => {
         // given a GPT-5.1-codex model ID
         const variant = getHighVariant("gpt-5.1-codex")

src/hooks/think-mode/switcher.ts

@@ -65,8 +65,6 @@ const HIGH_VARIANT_MAP: Record<string, string> = {
   "gpt-5-4": "gpt-5-4-high",
   "gpt-5-4-chat-latest": "gpt-5-4-chat-latest-high",
   "gpt-5-4-pro": "gpt-5-4-pro-high",
-  "gpt-5-4-mini": "gpt-5-4-mini-high",
-  "gpt-5-4-nano": "gpt-5-4-nano-high",
   // Antigravity (Google)
   "antigravity-gemini-3-1-pro": "antigravity-gemini-3-1-pro-high",
   "antigravity-gemini-3-flash": "antigravity-gemini-3-flash-high",