Add Cohere instrumentation package scaffolding

[Nik-Reddy]

Description

Adds a scaffold-only Cohere V2 instrumentation package as PR 1 of 4 tracked in #56. The CohereInstrumentor sets up tracer, logger, and meter providers but does not yet wrap any Cohere client methods.

Ported from open-telemetry/opentelemetry-python-contrib#4418, adapted to the new-repo conventions:

• Package name: opentelemetry-instrumentation-genai-cohere
• Import path: opentelemetry.instrumentation.genai.cohere
• Class: CohereInstrumentor
• Cohere SDK floor: cohere >= 5.13.0 (V2 GA floor; 5.0.0 lacks ClientV2)
• Python: 3.10, 3.11, 3.12, 3.13, 3.14
• OTel pins: opentelemetry-api ~= 1.40, opentelemetry-instrumentation ~= 0.61b0, opentelemetry-semantic-conventions ~= 0.61b0, opentelemetry-util-genai >= 1.0b0.dev

This mirrors the opentelemetry-instrumentation-genai-claude-agent-sdk scaffold shape.

Scope

• New package skeleton (src/, tests/, examples/, pyproject.toml, README.rst, LICENSE)
• 7 smoke tests covering instantiation, dependency reporting, instrument/uninstrument cycle, idempotent calls, no-provider fallback, and required-attribute presence
• Workspace registration: root pyproject.toml, tox.ini, eachdist.ini, uv.lock, and regenerated instrumentation/README.md
• Example placeholders (examples/manual and examples/zero-code) with explicit scaffold disclaimers per Cohere V2 instrumentation: continue scaffold + chat completions from my previous work opentelemetry-python-contrib#4418 #56
• Towncrier changelog fragment (.changelog/102.added)

Not in this PR (follow-ups per #56)

• PR 2: chat completions instrumentation (sync, async, non-streaming)
• PR 3: streaming
• PR 4: conformance tests

Validation

• uv lock succeeds; cohere v7.0.2 added with transitive deps
• tox -e generate regenerates instrumentation/README.md with the cohere row alphabetically inserted
• uv run ruff check instrumentation/opentelemetry-instrumentation-genai-cohere/ passes
• pytest passes 7/7 on both latest and oldest dep sets across the full Python 3.10-3.14 matrix

Closes part of #56.

[Nik-Reddy]

@lzchen PR is rebased and all checks are passing now. Could you please merge it when you get a chance? Thanks!

[lzchen]

Hi @Nik-Reddy , will have to wait for a maintainer to merge.

[Nik-Reddy]

@lmolkova all checks are passing. This is the scaffold-only Cohere package PR from the roadmap in #56.

Could you please take a look when you get a chance? Thanks!