v1.8.0

Additive (MINOR) release: the two deferred per-chord harmony descriptors from the §6.3.1 FEP.
Backward-compatible — a 1.0.0 pack is also a valid 1.8.0 pack, and older readers ignore the new
optional fields.

Added

• Chord-template harmony descriptors (spec §6.6): two
  OPTIONAL template fields that annotate the chord shape for teaching/display, never grading (the
  honesty rule — a grader MUST NOT score them) — caged (the CAGED-system shape the fingering
  derives from: one of C/A/G/E/D) and guideTones (chromatic semitone offsets 0–11
  above the chord root marking the quality-defining tones, typically the 3rd and 7th, e.g. a
  dominant-7 → [4, 10]). Both are key-independent shape properties, so they ride the template
  alongside voicing. Schema: caged (enum) + guideTones (int array) on $defs/template in
  schemas/arrangement.schema.json; exercised by the extended
  example (the Em template → caged: "E", guideTones: [3]). Completes the §6.3.1 FEP, whose
  caged/guideTones were deferred in 1.7.0.