libs/genai/v3.0.0

Changes since libs/genai/v2.1.12

release(genai): 3.0.0 (#1249)
release: 3.0.0 (langchain-v1) (genai, vertexai, community) (#1194)
docs: fix Griffe warnings (#1236)
test: use gemini-flash-lite-latest (#1230)
chore(genai): update from gemini-1.5-flash to gemini-2.5-flash (#1221)
fix(genai): Fix outdated doc for max_output_tokens default value (#1209)
fix(genai): preserve field descriptions and enum values for Union types with None in function schemas (#1092)
chore: bump lockfiles, resolve linting (genai, vertex, community) (#1203)
refactor(genai): test_chat_models.py (#1202)
feat(genai): handle all finish messages for AQA (#1201)
fix(genai): extract and include metadata (#941)
fix(genai): defer async client init for embeddings; avoid eager loop creation (#1183)
fix(genai): update json_mode to json_schema for structured output methods (#1188)
chore(genai): update model names in tests (#1187)
docs(genai): enhance structured output methods docstring (#1186)
test(genai): add test for ChatGoogleGenerativeAI class transport check (#831)