…onse IDs

Addresses 4 critical OpenTelemetry span issues in LiteLLM:

Issue #3: Remove redundant attributes from raw_gen_ai_request spans
- Removed self.set_attributes() call that was duplicating all parent span
  attributes (gen_ai.*, metadata.*) onto the raw span
- Raw span now only contains provider-specific llm.{provider}.* attributes
- Reduces storage and eliminates search confusion from duplicate data

Issue #4: Prevent attribute duplication on litellm_proxy_request parent span
- When litellm_request child span exists, removed redundant
  set_attributes() call on the parent proxy span
- Child span already carries all attributes; parent duplication doubles
  storage and complicates search

Issue #5: Fix orphaned guardrail traces
- Guardrail spans were created with context=None when no parent proxy span
  existed, resulting in orphaned root spans (separate trace_id)
- Added _resolve_guardrail_context() helper to ensure guardrails always
  have a valid parent (litellm_request or proxy span)
- Applied fix to both _handle_success and _handle_failure paths

Issue BerriAI#8: Add gen_ai.response.id for embeddings and image generation
- EmbeddingResponse and ImageResponse types don't have provider response IDs
- Added fallback to standard_logging_payload["id"] (litellm call ID) for
  correlation across LiteLLM UI, Phoenix traces, and provider logs
- Completions still use provider ID (e.g. "chatcmpl-xxx") when available

Tests added:
- TestRawSpanAttributeIsolation: Verify raw span has no gen_ai/metadata attrs
- TestNoParentSpanDuplication: Verify parent span doesn't get duplicated attrs
- TestGuardrailSpanParenting: Verify guardrails are children (not orphaned)
- TestResponseIdFallback: Verify response ID set for all call types

All existing OTEL tests pass (73 passed, 14 pre-existing protocol failures).

Co-Authored-By: Claude Haiku 4.5 <[email protected]>

V0 docs

- Skip short-circuit for providers that have a BaseAnthropicMessagesConfig
  (bedrock, vertex_ai, azure_ai, anthropic) — they use the agentic loop
  which includes a follow-up LLM synthesis step. Short-circuiting would
  return raw search text instead of an LLM-synthesized answer.
- Add fallback to litellm.get_llm_provider() for custom_llm_provider
  derivation when litellm_params is overwritten by kwargs.
- Add test for bedrock guard.

Addresses Greptile review comments #3 and #4.