feat(skills): persona/JTBD taxonomy, curl-able hosting, catalog browser, b2c-operator plugin

[clavery]

Refactor of how we present and deliver agent skills, adapting Sentry-for-AI's curl-first distribution while keeping our local-skill harness model. Plan of record: PLAN_SKILL_PRESENTATION.md.

What changed

Taxonomy (hybrid metadata)

• Per-skill persona / category / tags now live in each SKILL.md frontmatter (source of truth, edited with content). The SDK parser ignores them, so this is non-breaking across all IDE targets.
• Closed vocabulary in skills/taxonomy.schema.json (CI-enforced — frontmatter can't invent buckets).
• Generated consumer manifest skills/taxonomy.generated.json (committed, DO-NOT-EDIT, freshness-checked in CI).
• Two active personas: developer (41) + operator (16) = 57 governed skills. merchant is defined but active: false (deferred).

Curl-able hosting

• The docs build now publishes the entire skills/** tree (SKILL.md + every references/*.md) plus a machine-readable skills-index.json and an agent-friendly skills.txt, with absolute URLs and a "use curl -sL, not WebFetch" fidelity note. Cold agents / CI can fetch guidance with no install.

Interactive catalog

• New <skills-catalog /> Vue browser embedded on /guide/agent-skills: persona→category tree, tag cloud, search, and one-click copy curl per skill or for all matches. Build-time data loader (SSR-safe, no runtime fetch).

Doc page split

• /guide/agent-skills is now a quick-start-first showcase (keeps its slug — the most-linked URL); exhaustive per-IDE install detail moved to a new /guide/install-skills page. Inbound anchors repointed.

b2c-operator persona plugin

• A new plugin assembled by scripts/assemble-personas.mjs from the 16 operator-tagged skills (deploys, sandboxes, jobs, logs, debugging, edge/MRT, access admin) drawn across b2c-cli/b2c. Generated + committed (DO-NOT-EDIT), with a CI drift check. Each skill is still authored once in its home plugin.
• Registered across skills/plugins.json (flagged generated so it's published but not double-counted), .claude-plugin/marketplace.json, the SDK SkillSet/SKILL_SOURCES/ReleaseInfo, version sync, and a CLI overlap warning.

Tooling & guards (new CI skills job)

• scripts/validate-skills.mjs --check (frontmatter + reference-link resolution + manifest freshness), assemble-personas.mjs --check (drift), check-skills-hosting.mjs (curl URLs resolve), check-doc-anchors.mjs (page-split anchor guard).

Incidental fixes

• 6 pre-existing off-by-one cross-plugin links in b2c-scapi-shopper/b2c-scapi-admin (../../b2c-cli → ../../../b2c-cli).
• A stale #reading-log-files anchor in docs/cli/logs.md.

Follow-ups (deferred by design)

• merchant persona activation + a b2c-merchant bundle (only 3 merchant skills today).
• A b2c-developer bundle (low value — near-union of existing plugins).