Small joys: Codex audit #2 fixes (route resolution, noindex, sense/tone, exclude-current re-pick)

- Admin joy item route moved to /api/admin/joys/{kind}/items/{item_id} so the
  /add and /repick verbs resolve to their own routes instead of 422-ing as a
  non-int item id (the launch blocker). Frontend mutate URL updated to match.
- Re-pick now excludes the currently-shown item: the endpoint reads today's
  daily pool_id and passes it as `avoid`, so "Re-pick today" yields a different
  item. Added `avoid` to pick_daily/_candidates across wotd/quote/onthisday.
- WOTD sense selection: the LLM now proposes word + intended part of speech, and
  _lookup prefers that sense (fixes "serene" returning the archaic noun).
- On This Day tone prompt tightened to favor genuinely uplifting events and
  exclude merely procedural/political-administrative ones.
- Caddy @hidden now also noindexes /word /quote /onthisday /admin (+ .html).
- Regression tests: add/repick resolve (401 not 422), add/feature/block/delete,
  re-pick excludes current; WOTD pos-preference + proposal parsing units.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

deploy/caddy/Caddyfile.snapshot

@@ -60,7 +60,7 @@ upbeatbytes.com {
 		# Hidden in-progress prototypes — keep crawlers out at the HTTP level (the JS
 		# <meta robots> isn't seen by non-JS bots since the static shell is generic).
 		@hidden path /home2 /home3 /word /word.html /quote /quote.html /onthisday /onthisday.html /admin /admin.html
-		header @hidden X-Robots-Tag "noindex, nofollow"
+		header @hidden X-Robots-Tag "noindex, nofollow"
 
 		# Content-hashed assets never change for a given URL — cache them forever.
 		@immutable path /_app/immutable/*