feat(anthropic): Add gen_ai.system attribute to spans

[ericapisani]

Add the gen_ai.system span attribute (set to "anthropic") to the Anthropic integration.

Other AI integrations (OpenAI, Langchain, Google GenAI, LiteLLM, Pydantic AI) already set this attribute, but it was missing from the Anthropic integration. The attribute is set in _set_input_data() which is called for every span (streaming/non-streaming, sync/async).

Refs PY-2135
Closes #5657

[linear-code]

PY-2135 [Anthropic integration] Add `gen_ai.system` to spans

[github-actions]

Semver Impact of This PR

🟡 Minor (new features)

📋 Changelog Preview

This is how your changes will appear in the changelog.
Entries from this PR are highlighted with a left border (blockquote style).

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New Features ✨

Pydantic Ai

• Support ImageUrl content type in span instrumentation by ericapisani in #5629
• Add tool description to execute_tool spans by ericapisani in #5596

Other

• (anthropic) Add gen_ai.system attribute to spans by ericapisani in #5661

• (crons) Add owner field to MonitorConfig by julwhitney13 in #5610
• (otlp) Add collector_url option to OTLPIntegration by sl0thentr0py in #5603

Bug Fixes 🐛

• (celery) Propagate user-set headers by sentrivana in #5581
• (utils) Avoid double serialization of strings in safe_serialize by ericapisani in #5587
• Enable unused import ruff check and fix unused imports by sentrivana in #5652

Documentation 📚

• (openai-agents) Remove inapplicable comment by alexander-alderman-webb in #5495
• Add AGENTS.md by sentrivana in #5579
• Add set_attribute example to changelog by sentrivana in #5578

Internal Changes 🔧

Docs

• Remove agentic codebase documentation workflows by dingsdax in #5655
• Switch agentic workflows from Copilot to Claude engine by dingsdax in #5654
• Add agentic workflows for codebase documentation by dingsdax in #5649

Openai Agents

• Do not fail on new tool fields by alexander-alderman-webb in #5625
• Stop expecting a specific function name by alexander-alderman-webb in #5623
• Set streaming header when library uses with_streaming_response() by alexander-alderman-webb in #5583
• Replace mocks with httpx for streamed responses by alexander-alderman-webb in #5580
• Replace mocks with httpx in non-MCP tool tests by alexander-alderman-webb in #5602
• Replace mocks with httpx in MCP tool tests by alexander-alderman-webb in #5605
• Replace mocks with httpx in handoff tests by alexander-alderman-webb in #5604
• Replace mocks with httpx in API error test by alexander-alderman-webb in #5601
• Replace mocks with httpx in non-error single-response tests by alexander-alderman-webb in #5600
• Remove test for unreachable state by alexander-alderman-webb in #5584
• Expect namespace tool field for new openai versions by alexander-alderman-webb in #5599

Other

• (graphene) Simplify span creation by sentrivana in #5648
• (httpx) Resolve type checking failures by alexander-alderman-webb in #5626
• (pyramid) Support alpha suffixes in version parsing by alexander-alderman-webb in #5618
• (rust) Don't implement separate scope management by sentrivana in #5639
• (strawberry) Simplify span creation by sentrivana in #5647
• Remove custom warden action by sentrivana in #5653
• Add httpx to linting requirements by alexander-alderman-webb in #5644
• Remove CodeQL action by sentrivana in #5616
• Normalize dots in package names in populate_tox.py by alexander-alderman-webb in #5574
• Do not run actions on potel-base by sentrivana in #5614

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[github-actions]

Codecov Results 📊

✅ 13 passed | Total: 13 | Pass Rate: 100% | Execution Time: 12.47s

All tests are passing successfully.

❌ Patch coverage is 0.00%. Project has 14059 uncovered lines.

Files with missing lines (1)

File	Patch %	Lines
anthropic.py	9.03%	⚠️ 252 Missing

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