Resolve 0.1.0 provider qualification blockers

[stefan-jansen]

Resolves the final provider qualification blockers for 0.1.0.

• Normalizes surrounding Alpaca credential whitespace before constructing HTTP headers.
• Rejects credentials that normalize to empty.
• Adds regression coverage for the trailing newline reproduced by live contract run 31313306422.
• Records CryptoCompare as included but unverified for 0.1.0 because account registration is unavailable.
• Removes only CryptoCompare from mandatory 0.1.0 contract evidence while retaining its adapter and optional contract workflow.

Verification:

• 3,571 offline tests passed.
• Focused provider and release-policy tests passed after the final verifier refinement.
• Ruff, formatting, ty, and strict MkDocs passed.

[Copilot]

Pull request overview

This PR tightens release-qualification verification for provider contract runs and hardens Alpaca authentication by normalizing credential whitespace, while updating documentation to reflect CryptoCompare’s “included but unverified” status for the 0.1.0 release process.

Changes:

• Normalize Alpaca API credentials by stripping surrounding whitespace and reject credentials that normalize to empty; add regression tests for newline/whitespace cases.
• Update provider-contract verification policy by removing CryptoCompare from REQUIRED_CONTRACTS and introducing UNVERIFIED_CONTRACTS reporting + tests.
• Update docs/README to communicate CryptoCompare’s unverified (not release-qualified) status for 0.1.0.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
src/ml4t/data/providers/alpaca.py	Strip surrounding whitespace from resolved API credentials before building auth headers; enforce non-empty credentials.
tests/test_alpaca_provider.py	Add regression tests for whitespace/newline credentials and local rejection of whitespace-only credentials.
scripts/verify_provider_contract_runs.py	Remove CryptoCompare from required contracts and add UNVERIFIED_CONTRACTS reporting.
tests/test_provider_contract_verification.py	Extend verification tests to assert CryptoCompare is unverified and not release-qualified.
README.md	Document CryptoCompare as included but not release-qualified for 0.1.0.
docs/providers/index.md	Update provider comparison table + add a note about CryptoCompare not being release-qualified for 0.1.0.
docs/providers/cryptocompare.md	Mark CryptoCompare as included-for-evaluation and not release-qualified for 0.1.0; remove specific tier claims.
docs/getting-started/provider-selection.md	Update selection guidance/flowchart and comparison matrix to reflect CryptoCompare’s unverified status.

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