Refine onboarding graph controls and status visibility

[kiranfin]

User Story

As a project manager, I want the onboarding graph controls and statuses to be unambiguous, so that I can edit and review a path without guessing what each control does.

Context & Motivation

Several graph controls are difficult to interpret even though the graph itself was received positively.

Acceptance Criteria

• A step with a pending skip request displays a visible status indicator on its graph node.
• The current zoom percentage can be entered directly as a number.
• Invalid zoom values are clamped to the supported range.
• “Add Step” is visually separated from graph navigation controls.
• The add-step control includes a clear label or short explanation.
• The phase-level “Questions” tab is removed or relocated to the phase details where the knowledge check is managed.
• All graph controls remain keyboard-accessible.

Technical Notes

Reproduce this against the branch or build used in the UX test before implementation. A repo-wide search of the current main found no PM-facing onboarding path/graph editor at all (no zoom control, no "Add Step" control, no phase-level "Questions" tab, no route referencing it). The only graph component present is DiagramCanvas.tsx, a read-only competency-dependency diagram shown to hires on the Board page — it has no PM editing controls and does not match this description. Confirm whether the tested editor exists on a different branch, was a prototype/mockup, or is genuinely not yet merged before scoping this work.

[kiranfin]

Core problem (no PM editor) was fixed in PR #228 (Sep 21). Still open:

• Zoom percentage cannot be entered directly as a number (only +/- buttons and reset-to-100%)
• The add control ("New phase") has no visible label, only a tooltip/aria-label

Therefore closing this issue.