feat: [ENG-2536] add ByteRover onboarding tour skill

[wzlng]

Add a guided 90-second onboarding skill that runs when a user asks "Show me how ByteRover works" (or any semantic equivalent). The tour captures the user's persona and the pain that brought them to ByteRover, persists both locally, and demonstrates how ByteRover ends the re-explain tax — all without an account, API key, or provider config.

src/server/templates/skill/onboarding.md (new):

• Msg 1: trust opener (no command names) → one-sentence concept primer → quick interview (identity + pain in one open question) → human-reaction beat before curate → visible artifact with pain bullet + sticky label ("re-explain tax") + behavioral commitment → 2-beat concept map with visual separation before pause
• Msg 2: named action ("brv query"), one-line retrieval summary, conditional bonus-context branch when existing project knowledge is found, identity-and-pain reflection, future-self demonstration of the pain ending, loop name + cross-session promise
• Msg 3: where memory lives (one sentence, no commands) → activation step that detects CLAUDE.md/AGENTS.md/etc. and offers to curate as starter project context (or prompts for one rule) → done signal with two equal-weight paths (curate more vs. resume work) so users exit without homework
• Spec guards: don't manufacture pains, don't overpromise on out-of-scope pains, don't turn the artifact into a confirmation, don't tailor with hollow phrases, don't auto-fire next message

src/server/templates/skill/SKILL.md:

• Add First-Turn Routing block before the Iron Law that hands off to onboarding.md on tour/intro/walkthrough requests
• Update frontmatter description so the skill router activates the skill on tour-related phrasings

src/server/infra/connectors/skill/skill-connector-config.ts:

• Add onboarding.md to SKILL_FILE_NAMES so the connector copies it during install

[DatPham-6996]

LGTM:
I've tested on openclaw/hermes multtiple times, it worked expectedly
openclaw

hermes