feat: add Google Gemini tool support (php-llm#331)

Add tool support to Google Gemini.

Extracted from php-llm#320 with updates after php-llm#326

Co-authored-by: Vin Souza <vin@8sistemas.com>

feat: add support for mistral (php-llm#291)

* [x] text generation
* [x] streaming
* [x] tool calling
* [x] image input
* [x] structured output
* [x] embeddings
* [x] examples
* [x] documentation

Implementation is basically functional, but has following flaws to be
resolved:
1. tool schema differs in a breaking way from GPT - extension point is a
MUST
2. duplication of stream, message conversion and tool calling
3. error handling - once again

refactor: simplify transformers implementation by adding specific Pla…

…tform (php-llm#314)

Similar to php-llm#312

fix: missing namespace when upserting in Pinecone store (php-llm#310)

When adding documents, it does not take configured namespace into
consideration, this PR fixes it.

refactor: use lib specific exceptions instead of native ones (php-llm…

…#293)

feat: add support for TransformersPHP for model runtime in PHP (php-l…

…lm#280)

Sitting on top of https://github.com/CodeWithKyrian/transformers-php

docs: add section about chain in chain (php-llm#268)

refactor: introduce tool metadata factory interface (php-llm#249)

Preparation for different tool metadata sources, e.g. config or mcp
based

ci: use `bug` instead of `fix` label (php-llm#246)

chore: require PHPStan and Rector 2 (php-llm#230)

* Require PHPStan and Rector 2

* fix

* fix: phpstan 2.0 issues (php-llm#231)

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Co-authored-by: Christopher Hertel <mail@christopher-hertel.de>