feat(agent): add raw control sender

[GregHolmes]

Summary

• Add public sync and async send_raw() methods for protocol-transparent Agent control-frame bridges.
• Serialize mapping inputs without model validation and preserve serialized JSON strings unchanged.
• Freeze the generated socket-client patch and cover both input forms on both clients.

Closes #785

Validation

• 32 tests in tests/custom/test_socket_client_shims.py
• mypy src tests/typecheck/compat_aliases.py
• ruff check on changed files
• All validation ran in a clean Python 3.12 container

[github-actions]

Package	Line Rate	Branch Rate	Complexity	Health
src.deepgram	97%	94%	0	✔
src.deepgram.agent	100%	100%	0	✔
src.deepgram.agent.v1	98%	100%	0	✔
src.deepgram.agent.v1.settings	100%	100%	0	✔
src.deepgram.agent.v1.settings.think	100%	100%	0	✔
src.deepgram.agent.v1.settings.think.models	97%	100%	0	✔
src.deepgram.auth	100%	100%	0	✔
src.deepgram.auth.v1	100%	100%	0	✔
src.deepgram.auth.v1.tokens	97%	100%	0	✔
src.deepgram.core	88%	81%	0	➖
src.deepgram.errors	100%	100%	0	✔
src.deepgram.helpers	100%	95%	0	✔
src.deepgram.listen	100%	100%	0	✔
src.deepgram.listen.v1	98%	93%	0	✔
src.deepgram.listen.v1.media	97%	100%	0	✔
src.deepgram.listen.v2	98%	93%	0	✔
src.deepgram.manage	100%	100%	0	✔
src.deepgram.manage.v1	100%	100%	0	✔
src.deepgram.manage.v1.models	96%	100%	0	✔
src.deepgram.manage.v1.projects	97%	100%	0	✔
src.deepgram.manage.v1.projects.billing	100%	100%	0	✔
src.deepgram.manage.v1.projects.billing.balances	96%	100%	0	✔
src.deepgram.manage.v1.projects.billing.breakdown	97%	100%	0	✔
src.deepgram.manage.v1.projects.billing.fields	97%	100%	0	✔
src.deepgram.manage.v1.projects.billing.purchases	97%	100%	0	✔
src.deepgram.manage.v1.projects.keys	96%	100%	0	✔
src.deepgram.manage.v1.projects.members	97%	100%	0	✔
src.deepgram.manage.v1.projects.members.invites	96%	100%	0	✔
src.deepgram.manage.v1.projects.members.scopes	96%	100%	0	✔
src.deepgram.manage.v1.projects.models	96%	100%	0	✔
src.deepgram.manage.v1.projects.usage	98%	100%	0	✔
src.deepgram.manage.v1.projects.usage.breakdown	97%	100%	0	✔
src.deepgram.manage.v1.projects.usage.fields	97%	100%	0	✔
src.deepgram.read	100%	100%	0	✔
src.deepgram.read.v1	100%	100%	0	✔
src.deepgram.read.v1.text	98%	100%	0	✔
src.deepgram.self_hosted	100%	100%	0	✔
src.deepgram.self_hosted.v1	100%	100%	0	✔
src.deepgram.self_hosted.v1.distribution_credentials	96%	100%	0	✔
src.deepgram.speak	100%	100%	0	✔
src.deepgram.speak.v1	98%	97%	0	✔
src.deepgram.speak.v1.audio	91%	80%	0	✔
src.deepgram.speak.v2	98%	93%	0	✔
src.deepgram.speak.v2.audio	100%	100%	0	✔
src.deepgram.voice_agent	100%	100%	0	✔
src.deepgram.voice_agent.configurations	95%	100%	0	✔
src.deepgram.voice_agent.variables	95%	100%	0	✔
Summary	95% (6507 / 6822)	91% (1419 / 1552)	0	✔

Scope: hand-maintained SDK logic. Fern-generated data models (types/, requests/), package __init__.py files, version.py, and the unused core/http_sse/ scaffolding are excluded — see .coveragerc. Unscoped whole-package coverage is ~70%.