[matthewrball]

Why

For a new task, the folder chooser sits in the title bar away from the prompt. The generic New Task title repeats the sidebar action without identifying a saved task.

What this PR adds

• Place the existing folder selector directly above the composer for drafts, and omit the redundant draft header title.
• Keep saved-task titles, project selection, and branch context in the header, including saved tasks with an empty transcript.
• Preserve the shared popup, shortcuts, focus behavior, and local/remote project selection; long project and branch labels remain bounded.

Extracted from #1347 so the changes can be reviewed and merged independently. This PR targets master and leaves Search behavior unchanged.

Preview

Native fixture task pane, cropped to this PR's scope.

Verification

• At 37fa08a6, cargo test -p maple-agent-app --bin maple-agent --locked -- --test-threads=2: 1,141 passed, 0 failed, 2 ignored.
• Coverage includes 16 draft-layout states, saved-task headers, popup interactions, and a resize-aware 640×480 regression across eight combinations with long labels and popup containment.
• Formatting, diff checks, and independent source review passed. Native folder-selector placement and popup behavior were checked in the isolated fixture.
• CI exposed an existing command-test fixture missing GPUI's asynchronous test setup. The one-line fixture correction preserves its assertions and production behavior; the current head needs a new CI result.

Local checks used Rust 1.96.0 and Xcode 27.1. On the previous head, upstream lint, macOS, and Windows checks passed; the test lane failed on the fixture issue above. Current-head CI still needs maintainer approval and successful completion.

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