chore(skills): prune dead BYOK branch from resume-import docs

[claude-dataviking]

What

Prunes the dead BYOK (bring-your-own-key) branch from the bundled skill
docs. BYOK was removed from the product in 2026-07 — user compute is now
the connected agent itself (the "you are the model" D11 agent-assist
path), and platform-run AI is beta-gated. The skill docs still described
an "if a BYOK LLM key is configured, use the provider path" branch that
no longer exists.

Changes (docs-only)

• skills/traitprint-import-resume/SKILL.md — drop the "no BYOK key
  configured" conditional and the "if the user has a working key, pass
  --provider / let the configured key win; --no-assist errors when no
  key" branch. The agent-assist payload is now the primary and only
  user-compute path. Note that platform-run extraction is beta-gated
  (join at https://traitprint.com/beta).
• skills/shared/cli-reference.md — rewrite the import-resume
  reference from the --provider -> configured BYOK key -> agent-assist
  resolution order to the agent-assist payload behavior; note beta-gated
  platform extraction.
• CHANGELOG.md — entry under ### Changed.

The local-first CLI's deterministic paths (extract-text, batch
add-*, proposals, audit) are unchanged. The only remaining "API
key" mentions in skills are "no API key" framing that reinforces the D11
agent-is-the-model pattern.

Gates

.venv/bin/pytest -q (1028 passed, 3 skipped), ruff check src/ tests/,
and mypy src/ all green. No skill-registry or doc-truth test needed
updating.

Required follow-up after merge (not in this repo)

traitprint-cloud vendors these files byte-for-byte into
plugins/traitprint/skills/ at a pinned ref, enforced by a sync test.
After this merges, re-vendor and bump the pin:

• Bump SKILLS_SYNC_REF in traitprint-cloud/scripts/sync-plugin-skills.ts
  (currently 131dbc2a337406c4c80c15c4186dba14bc1e4ffb) to this PR's
  squash-merge commit SHA on main.
• Run npx tsx scripts/sync-plugin-skills.ts to re-vendor
  shared/cli-reference.md and traitprint-import-resume/SKILL.md
  (both in SKILLS_MANIFEST), then commit the re-vendored files together
  with the bumped pin so scripts/sync-plugin-skills.test.ts passes.

🤖 Generated with Claude Code