revert: restore code fallbacks for config defaults

This reverts commit 153fc21. With no fallback in code, the deploy
crash-looped: Coolify keeps an entry for every variable compose.yml has
referenced, and empty entries appear to reach the containers as empty
values instead of the compose defaults.

.env.example

@@ -25,8 +25,7 @@ ADMIN_IDS=
 # MUST end in _by_<this bot username>: Telegram requires that suffix on sets a
 # bot creates and refuses to edit sets it did not create, so the suffix is what
 # proves the pack is manageable. Created automatically, owned by OWNER_ID, on
-# the first /addsticker if it does not exist yet. Required by /addsticker:
-# the code has no fallback (compose.yml supplies this value as its default).
+# the first /addsticker if it does not exist yet. Unset = the default below.
 STICKER_PACK_NAME=miti99_by_miti99bot
 
 # SOURCE_COMMIT (commit SHA) is read at startup for the deploynotify owner DM.
@@ -45,16 +44,10 @@ LOL_PANDASCORE_TOKEN=
 # only when running the bot outside compose. Leave blank to fall back to text.
 RENDERER_URL=
 
-# ============================ Runtime =============================
-# Required: the code has no fallback. compose.yml supplies these values as its
-# defaults; set them yourself when running outside compose.
-# Log level: debug, info, warn, or error.
-LOG_LEVEL=info
-# Internal health server port.
-PORT=8080
-
 # ====================== Leave UNSET on self-host ==================
+# Defaults are correct for self-host:
 #   KV_PROVIDER          — auto-selects mongodb because MONGO_URL is set
+#   PORT                 — defaults to 8080 (internal health server)
 #   TELEGRAM_WEBHOOK_SECRET — long polling has no webhook
 #   GOLD_VNAPP_API_KEY   — gold module auto-fetches + caches the key to Mongo
 # Stock/coin/gold URL env overrides are not supported; modules use coded