fix(native.system): repair build-dashboard frontmatter, confirm via #opt link

[thinhnguyentruong]

Split out of #27 so it can land independently — #27 keeps the two new skills, which have open review comments. This half has none, and fix 1 is a live bug on main.

1. The description was invalid YAML

build-dashboard's description was a single-line plain scalar containing ": " (from Typical phrasings: ...). YAML does not allow that — gray-matter raises incomplete explicit mapping pair, so the frontmatter does not parse and the skill's entire trigger contract is unreadable.

Rewritten as a block scalar with the same four paragraphs it always had. No wording changed — this is purely the scalar style. Also adds the label field its sibling skills carry.

2. Plan confirmation closes with an option link

Workflow step 2 presented a plan and then waited on free text. It now ends with:

Build this dashboard?
[Yes — build it as planned](#opt)
[<another way to build it — as an instruction>](#opt)

The chat renders [text](#opt) as a clickable chip, and clicking it sends the link text verbatim as the user's next message.

The step spells out the two consequences of that, since neither is guessable from the markdown:

• the link is plain markdown, not a tool call, so nothing pauses the agent — it must end its turn and wait, or it builds against a plan the user never approved;
• the label becomes the user's message, so each one is written as the instruction they'd otherwise have typed.

The first link is always the approval; any others follow from the plan.

Note for reviewers

scripts/validate-frontmatter.js has a dedicated error path for bug 1 — including the hint "quote values that contain colons" — but globs plugins/**/SKILL.md only, so it validates 30 files and skips all 13 under native-skills/. Broadening that glob is a one-line change; happy to add it here or split it out.

Test plan

• Frontmatter parses as YAML; description round-trips complete (4 paragraphs)
• pnpm validate-links — all links valid
• pnpm validate-frontmatter — passes (note the coverage gap above)
• The option chip renders and round-trips in chat

[gemini-code-assist]

Caution

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