fix(ai): strip trailing newlines and whitespace from provider API keys (#1437)

[Shubh2-0]

Fixes #1437

Description

When provider API keys or env vars are loaded from secrets, .env files or command line expansions (e.g. cat keyfile), they often contain trailing newlines (\n) or surrounding whitespace. When passed into HTTP client Authorization headers, Java HTTP clients reject the raw 0x0a newline byte and throw 'Unexpected char 0x0a in Authorization value'.

Changes Made

1. At Ingestion: Updated \EnvVarLookup.lookup()\ and \EnvVarLookup.allWithPrefix()\ to sanitize retrieved values via .strip(), ensuring trailing newlines and whitespace are stripped at resolution time.
2. At API Client Constructors: Added defensive .strip()\ sanitization across provider HTTP API clients (\OpenAIChatCompletionsApi, \OpenAIEmbeddingsApi, \AnthropicMessagesApi) when building authorization headers.
3. Unit Tests: Added \EnvVarLookupTest\ and updated \OpenAITest\ to verify trailing newline stripping.

Verification

• Tested with \EnvVarLookupTest\ (verifying \n stripping on secret resolution).
• Ran provider test suites via ./gradlew :conductor-ai:test.