fix(dora-maas-client): update outfox-openai dependency to v0.7.0

[prabhaharanv]

Changes:

• Bump outfox-openai from 0.2.0 to 0.7.0 and pin to rev 05309e0
• Enable required "chat-completion" feature flag
• Fix type mismatch: use ChatCompletionRequestSystemMessageContent::Text instead of PartibleTextContent::Text for system message content

📋 Summary

dora-maas-client fails to compile because outfox-openai = "^0.2.0" does not match any version in the outfox repository. The crate was renamed from novel-openai to outfox-openai starting at version 0.6.0 — version 0.2.0 never existed. This PR updates the dependency to the correct version and fixes a resulting type mismatch.

🔗 Related Issues

Closes #59

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🧠 Context

The outfox-openai crate history in the outfox repo:

• 800e8af — novel-openai v0.3.0 (initial commit)
• 054bff5 — novel-openai v0.6.0
• 175b161 — renamed to outfox-openai v0.6.0
• 05309e0 — outfox-openai v0.7.0 (latest)

Since outfox-openai v0.2.0 never existed, Cargo fails immediately with:
error: failed to select a version for the requirement outfox-openai = "^0.2.0"
candidate versions found which didn't match: 0.7.0

Additionally, v0.7.0 requires the chat-completion feature flag to expose spec::chat::* types and their transitive dependency on futures. Without it, the types used by the source code are behind #[cfg] gates.

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🛠️ Changes

• Cargo.toml: Update outfox-openai from 0.2.0 to 0.7.0, pin to git rev 05309e0, and enable the chat-completion feature
• main.rs: Add ChatCompletionRequestSystemMessageContent to imports and use it instead of PartibleTextContent::Text for the system message content field (type changed between API versions)

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🧪 How you Tested

1. cargo build --manifest-path node-hub/dora-maas-client/Cargo.toml — passes (warnings only, all pre-existing)
2. cargo check --manifest-path node-hub/dora-maas-client/Cargo.toml — passes
3. cargo test --manifest-path node-hub/dora-maas-client/Cargo.toml — 5 passed, 2 failed (test_chinese_character_segmentation, test_markdown_cleaning — both are pre-existing failures in segmenter::tests, unrelated to this change; the original code doesn't compile at all)

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📸 Screenshots / Logs (if applicable)

Before fix:
error: failed to select a version for the requirement outfox-openai = "^0.2.0"
candidate versions found which didn't match: 0.7.0

After fix:
Finished dev profile [unoptimized + debuginfo] target(s) in 23.07s

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⚠️ Breaking Changes

• No breaking changes

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🧹 Checklist

Code Quality

• Code follows Rust idioms and project conventions
• cargo fmt run
• cargo clippy passes without warnings

Testing

• Tests added/updated
• cargo test passes locally without any error

PR Hygiene

• PR is small and focused (one logical change)
• Branch is up to date with main
• No unrelated commits
• Commit messages explain why, not only what

Documentation

• Public APIs documented
• README / docs updated (if needed)

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🚀 Deployment Notes (if applicable)

None.

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🧩 Additional Notes for Reviewers

• The 2 test failures in segmenter::tests are pre-existing — the original main branch code doesn't compile at all due to this dependency bug, so those tests were already broken before this PR.
• The build warnings (unused variables, dead code) are also all pre-existing.
• cargo fmt and cargo clippy checkboxes are left unchecked because the warnings are pre-existing across the entire crate, not introduced by this change. Running cargo fmt/clippy --fix would create unrelated changes.