Introduces watch/, a real Pebble watchapp (built via pebble build) that

shows the daily tarot/astrology reading on-device: persistence, reading
computation, and UI screens, driven by the existing engine/interpreter
code linked in unchanged where possible.

Required engine-side changes to make that linking work:
- A compact low-precision ephemeris (lowprec_ephemeris.c) replacing the
  vendored ~127KB Astronomy Engine, which doesn't fit the watch's ~64KB
  app budget.
- Hand-rolled sqrt/atan2/sin/cos replacements for that ephemeris and
  astro.c's Ascendant calculation - Pebble's statically-linked libm
  hard-faults on real hardware under this app's -fPIE link for all four.
- narrative.c/guidance.c refactored from FILE*/fprintf onto snprintf-
  based buffers, since Pebble's SDK blocks fprintf at compile time.

engine/i18n/de.lang

@@ -22,6 +22,12 @@ ui.transiting=Transit
 ui.natal=natal
 ui.orb=Orbis
 
+# --- Nur die Watch-App (watch/src/c/main.c) - wird vor der ersten
+# Einrichtung ueber die Konfigurationsseite gezeigt, wenn noch keine
+# Geburtsdaten fuer eine Deutung vorliegen ---
+ui.setup_required_title=Einrichtung erforderlich
+ui.setup_required_body=Öffne die Einstellungen dieser App in der Pebble-App, um deine Geburtsdaten einzugeben, und starte Deck in a Dash danach erneut.
+
 # --- Planeten (astro.c) ---
 body.sun=Sonne
 body.moon=Mond

engine/i18n/en.lang

@@ -29,6 +29,12 @@ ui.transiting=Transiting
 ui.natal=natal
 ui.orb=orb
 
+# --- Watch app only (watch/src/c/main.c) - shown before the first
+# config-page submission, when there's no birth data yet to compute a
+# reading from ---
+ui.setup_required_title=Setup Required
+ui.setup_required_body=Open this app's settings from the Pebble mobile app to add your birth details, then reopen Deck in a Dash.
+
 # --- Planets/luminaries (astro.c) ---
 body.sun=Sun
 body.moon=Moon