Give the interpreter real Celtic Cross meanings and --format/--lang support

- guidance.c now prints last, after the full spread; both it and main.c's
  new Celtic Cross readout pull real Waite card meanings via tarot_data.c
  instead of just naming cards.
- interpreter-cli gains --format text|html|json and --lang en|de, matching
  deck-engine - required linking engine/src/tarot_data.c and i18n.c into
  the interpreter binary (a narrow, documented exception to its earlier
  "no engine .c files" policy) and writing German translations for
  narrative.c's/guidance.c's own text.

docs/diagrams/architecture.dot

@@ -55,12 +55,6 @@ digraph architecture {
     { rank=same; binary; distimg; disti18n; runsh; props; }
   }
 
-  subgraph cluster_watch {
-    label="Pebble watchapp — not built yet";
-    style="dashed"; color=firebrick; fontsize=11; fontcolor=firebrick;
-    watch [label="watchapp C / UI\n(future)", fillcolor=white, color=firebrick, fontcolor=firebrick, style="rounded,dashed"];
-  }
-
   pdf -> tarot_data [label="sourced from", style=dotted, color=gray40];
 
   tarot -> rng;
@@ -78,6 +72,4 @@ digraph architecture {
   images -> distimg [label="`make images`\ncopies", style=dotted, color=gray40];
   langfiles -> disti18n [label="`make i18n`\ncopies", style=dotted, color=gray40];
   runsh -> props [label="reads at\nrun time", style=dotted, color=gray40];
-
-  watch -> reading [label="will call\nreading_generate()\ndirectly", style=dashed, color=firebrick, fontcolor=firebrick];
 }