feat: add continuity engine, manuscript import, and PR automation templates

[danjdewhurst]

• New src/continuity.js: deterministic continuity checks wired into a new
  'story continuity' command and folded into doctor, report, and next.
  Catches dead characters appearing after their died-in chapter, payoffs
  before plants, questions resolved before introduced, unfired Chekhov
  promises, POV/cast mismatches, chapter numbering gaps, completion-state
  contradictions, and broken continuity/state.md references.
• New schema fields: optional character died-in, and chapter/scene mentions
  for posthumous or flashback references that should stay legal.
• New src/import.js: 'story import' splits an existing manuscript (file or
  directory) into a new project with accurate word counts and registries,
  and prints recurring proper-name candidates for bible building.
• New examples/the-unraveled-thread: deliberately broken project whose
  exact findings are asserted by check-examples.js, doubling as the README
  demo and a regression test. Harbor example enriched with populated
  continuity state, a planted promise, and an open question.
• New templates/github: story-checks.yml CI for story repos and
  draft-next-chapter.yml for writing a book via scheduled chapter PRs.
• CLI failure summaries now use a failure message instead of repeating the
  success message. Docs, skills, JSON schema updated; version 0.3.0.

https://claude.ai/code/session_01XVwAnE2xRMVd7CZR4MrSU1