feat(discovery): batch questions and persist progress

[kcrmin]

Problem

Discovery currently asks one decision at a time and cannot persist section progress, estimated remaining questions, or grouped recommendations. Switching sessions can lose the distinction between recommendations and accepted decisions.

Acceptance

• Group independent routine questions with recommendations pending user submission.
• Keep high-impact questions explicit and accepted decisions separate.
• Persist current/remaining sections, estimated question range and harness readiness.
• Recover the same discovery state from a draft and an initialized/cloned project.
• Preserve old checkpoints and paired English/Korean documentation.
• Verify Go/CLI/schema behavior and plugin/document contracts.

Scope

First delivery slice for the requested Stackcord redesign (requests 1 and 10). Use Graphify for local code navigation; its index is not a shipped dependency. Existing governance PR #4 remains separate.