stdd-explorelisted

# stdd-explore — Lore 智者探詢 Opt-in skill (installed from `stdd-skills/`, not auto-loaded from the plugin's `skills/` directory). This is a conversational, thinking-partner skill: it produces at most one small note (a rejected-options list), never code, never a spec file itself. ## Step 0 — Entry triage (only when this change has no `STDD/<name>/` dir yet) Before doing anything else, check whether the target project already has an `STDD/<name>/` directory for this change. If it does NOT (this is the first time this change enters the pipeline), run this exact four-point check against the user's request. If ANY point matches, you SHALL NOT enter the explore flow below — instead reply "this change doesn't need the full STDD workflow, doing it directly" and STOP: 1. The change is a pure typo fix (no logic/behavior change). 2. The change is confined to one line (or a few contiguous lines of the same statement) in a single file, adds no new requirement/scenario, and touches no contract. 3. This is a pure Q&A request (the user wants an explanation/lookup of existing code or docs, not a change). 4. The user has already given explicit, step-by-step implementation instructions in the conversation — no new design decision is needed from explore/spec. If none of the four match, treat this as needing the full STDD flow and continue to Step 1. (If a `STDD/<name>/` dir already exists for this change, skip this triage — it only applies to a change's first entry.) ## Step 1