chore(main): release 0.21.0

[github-actions]

🤖 I have created a release beep boop

0.21.0 (2025-10-22)

⚠ BREAKING CHANGES

• chat event get's reasoning variant
• unify function and tool concepts
• remove explain functionality in 0.4 wit world
• introduce 0.4 wit world
• remove llama3 submodule in favour of inference provided tool calling

Features

• add reasoning trace to Message class (7f0b763)
• allow multiple tool calls (d60d81c)
• chat event get's reasoning variant (59aaff0)
• introduce 0.4 wit world (be3c855)
• message writer accepts reasoning events (ebe88e4)
• prototype agent decorator (28ec298)
• remove explain functionality in 0.4 wit world (ae125c7)
• remove llama3 submodule in favour of inference provided tool calling (f29dec0)
• remove logprobs from 0.4 chat event (d0f7ea2)
• unify function and tool concepts (bd48ed5)
• wit 0.4 is stable (6d5008f)

Bug Fixes

• only construct span exporter if corresponding env variable is set (79b1ac4)
• serialization of chat request (bee58ca)

Documentation

• add hans as author (f916d00)
• rename kernel to engine (f7a5434)
• rename project in rtd to pharia-skill (e2cf060)
• update readme with right command to run componentize-py (59a6e9f)

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