Scope generate_code_review_content to the window's team

[warp-agent-staging]

Description

Scopes the client-side POST /ai/generate_code_review_content call (commit-message autogen and PR title/body generation in GitDialog) to the window's team by sending X-Warp-Team-Uid.

Previously this request carried no team header. The server falls through GetActiveTeamOrFallbackToPrincipal → GetTeamForPrincipal, which picks the caller's lowest team id — an arbitrary team, not the one the window is actually working in. Since this endpoint's server handler (generate_code_review_content.go) writes billing metadata, an unscoped call attributed usage to the wrong team for any multi-team user whose window wasn't on their lowest-id team.

The team now comes from the window (ViewContext<GitDialog> → UserWorkspaces::team_context_for_view), resolved right before the model call so it can't drift to a fallback. That scope is threaded as a RequestTeamScope through DiffStateModel → LocalDiffStateModel → git_actions::{run_commit_chain, create_pr, generate_commit_message} → AIClient::generate_code_review_content, which is the one call site that actually sends the header (mirrors the /ai/multi-agent pattern from #15355).

The remote-server daemon path (RemoteDiffStateModel → RPC → ServerModel handlers) also calls this same endpoint, but the daemon is headless and has no window/team concept at all, so there's no live scope to resolve there. Those call sites now pass RequestTeamScope::none_for_headless_context(), explicitly, rather than guessing a team — this is unchanged behavior for that path (no header was sent before either).

Linked Issue

N/A — this PR was dispatched directly as part of a header-scoping cleanup pass, not from a tracked issue.

Testing

• ./script/format and cargo clippy -p warp --lib --tests -- -D warnings pass with no findings.
• cargo nextest run -p warp for code_review::, remote_server::, and server_api::ai:: (150 tests, 149 passed / 128 + 149 across both runs; the one failure, ambient_agent_headers_for_task_overrides_existing_cloud_agent_header, is a pre-existing sandbox limitation — it also fails on unmodified master here because the nsc namespace command is denied in this environment — and is unrelated to this change).
• No behavior test was added: this is a plumbing change (adding a header value) with no new branching logic to regress-test, and the endpoint's request/response shape is unchanged.
• Not manually verified end-to-end against a live multi-team account (no GUI/browser available in this environment); the header value itself is exercised by existing coverage of RequestTeamScope/TEAM_UID_HEADER from [multi-team] Scope multi-agent requests to a team #15355.

Screenshots / Videos

Not applicable — no UI change.

Agent Mode

• Warp Agent Mode - This PR was created via Warp's AI Agent Mode

[warp-agent-staging]

This PR was generated with Warp.

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