fix: Antigravity API compatibility and Gemini thinking tag leakage (#167)

* fix: ensure type:object in sanitized tool schemas for Antigravity API

The sanitizeSchemaForGoogle function strips unsupported JSON Schema
keywords like anyOf, but this can leave schemas with 'properties' and
'required' fields without a 'type' field. Both Google's Gemini API and
Anthropic via Antigravity require 'type: object' when these fields exist.

This fix adds a post-sanitization check that ensures type is set to
'object' when properties or required fields are present.

Fixes errors like:
- Gemini: 'parameters.properties: only allowed for OBJECT type'
- Anthropic: 'tools.6.custom.input_schema.type: Field required'

* fix: regenerate pi-ai patch with proper pnpm format

The patch now correctly applies via pnpm patch-commit, fixing:
- Thinking blocks: skip for Gemini, send with signature for Claude
- Schema sanitization: ensure type:object after removing anyOf
- Remove strict:null for LM Studio/Antigravity compatibility

Tested with all Antigravity models (Gemini and Claude).

* fix: strip thinking tags from block streaming output to prevent Gemini tag leakage

src/agents/pi-embedded-subscribe.ts

@@ -248,7 +248,9 @@ export function subscribeEmbeddedPiSession(params: {
   };
 
   const emitBlockChunk = (text: string) => {
-    const chunk = text.trimEnd();
+    // Strip any <thinking> tags that may have leaked into the output (e.g., from Gemini mimicking history)
+    const strippedText = stripThinkingSegments(stripUnpairedThinkingTags(text));
+    const chunk = strippedText.trimEnd();
     if (!chunk) return;
     if (chunk === lastBlockReplyText) return;
     lastBlockReplyText = chunk;