v1.0.3

fix: correct text shared-hero transitions on iOS and Android

Text heroes (and any non-image content) were cropped, mis-positioned, and
occasionally desynced because the flight machinery was tuned for opaque images.
- Flight content mode is now aspect-aware by mode: snapshot/text maps box->box
  with scale-to-fill (iOS .scaleToFill / Android FIT_XY) so glyphs land exactly
  on the destination and never crop or re-anchor; morph/zoom keep aspect-fill.
  Applies to both the engine flights and the interactive-return overlay.
- Fix a very fast left-edge swipe-back committing as a jump: pre-activation
  releases now route through the settle-observing release phase instead of
  guessing commit/cancel from a lagging presentation translation.
- Fix Android blank-bitmap heuristic false-positiving on sparse text: sample a
  full-area grid instead of a few centre points, so a real line of text is no
  longer judged blank (which suppressed its stash/fallback and delayed one hero
  of a sibling pair behind the in-place content-wait).
Add a Text hero example (list -> detail) demonstrating small one-line titles
growing into large headlines, and record the rationale in LESSONS_LEARNED.md.