Clarify .env vs sky-cam.conf split for toggles and private values

Rule is now consistent throughout:
- *_ENABLED flags are plain true/false in sky-cam.conf — flip them there
- Private values (URLs, credentials, location) go in .env only

sky-cam.conf:
- NTFY_ENABLED, EMAIL_ENABLED, MM_NOTIFY_ENABLED are now plain false (not
  using the ${VAR:-} pattern, which implied they could go in .env)
- NTFY_URL, EMAIL_TO, EMAIL_FROM, MM_NOTIFY_CHANNEL_ID use ${VAR:-} pattern
  so they are set in .env
- LATITUDE/LONGITUDE comment clarified with example .env lines

install.sh .env.example: updated notification comment to match

https://claude.ai/code/session_01C4jbd3waXG3eKZYbGUjLUQ

install.sh

@@ -280,10 +280,11 @@ env_example="$HERE/.env.example"
     echo "channel_id=your-daily-upload-channel-id-here"
     echo ""
     echo "# ── Notifications ───────────────────────────────────────────────────────────"
-    echo "# Also set NTFY_ENABLED=true / EMAIL_ENABLED=true / MM_NOTIFY_ENABLED=true"
-    echo "# in sky-cam.conf to activate the method."
+    echo "# Set the private values here, then flip the matching *_ENABLED toggle"
+    echo "# to true in sky-cam.conf."
     echo "#NTFY_URL=https://ntfy.sh/your-topic"
     echo "#EMAIL_TO=you@example.com"
+    echo "#EMAIL_FROM=skycam@localhost"
     echo "#MM_NOTIFY_CHANNEL_ID=your-notify-channel-id-here"
 } > "$env_example"
 echo "  wrote .env.example  (cp .env.example .env  then fill in real values)"

sky-cam.conf

@@ -158,13 +158,16 @@ MUSIC_DIR="${MUSIC_DIR:-$SCRIPT_DIR/music}"
 #   Google Maps — right-click your location → the first item shown is "lat, lon"
 #   Or: maps.google.com, drop a pin, coordinates appear in the URL and sidebar
 #
-# TIMEZONE must be a valid IANA name.  Look yours up at:
-#   https://en.wikipedia.org/wiki/List_of_tz_database_time_zones
-#   (use the value in the "TZ identifier" column, e.g. America/Chicago)
+# ── Location & timezone ───────────────────────────────────────────────────────
+# Set your real values in .env — do not put exact coordinates here since
+# this file is committed to git.  Add these three lines to your .env:
 #
-# Set your real values in .env — these placeholder defaults keep the file
-# shareable without leaking your exact location.
-LATITUDE="${LATITUDE:-25.0000}"
+#   LATITUDE=43.1234
+#   LONGITUDE=-76.5678
+#   TIMEZONE=America/Chicago
+#
+# Placeholder values below are used only if .env has not set them.
+LATITUDE="${LATITUDE:-0.0000}"
 LONGITUDE="${LONGITUDE:-0.0000}"
 TIMEZONE="${TIMEZONE:-America/New_York}"
 
@@ -336,19 +339,22 @@ AMBIENT_RETENTION_DAYS=30              # delete files older than this; 0 = keep
 # ntfy — push notifications, zero signup for self-hosted or free cloud tier:
 #   Self-hosted: https://docs.ntfy.sh/install/
 #   Cloud: pick any topic name at ntfy.sh (no account needed)
-NTFY_ENABLED="${NTFY_ENABLED:-false}"
-NTFY_URL="${NTFY_URL:-}"               # set in .env — keeps your topic URL out of git
+#   Set NTFY_URL=https://ntfy.sh/your-topic in .env, then flip the toggle below.
+NTFY_ENABLED=false
+NTFY_URL="${NTFY_URL:-}"
 
 # Email — requires the 'mail' command (package: mailutils or s-nail).
 # Configure outbound SMTP via /etc/ssmtp/ssmtp.conf or msmtp.
-#EMAIL_ENABLED=true
-#EMAIL_TO=you@example.com
-#EMAIL_FROM=skycam@localhost
+#   Set EMAIL_TO and EMAIL_FROM in .env, then flip the toggle below.
+EMAIL_ENABLED=false
+EMAIL_TO="${EMAIL_TO:-}"
+EMAIL_FROM="${EMAIL_FROM:-skycam@localhost}"
 
 # Mattermost text post — reuses mattermost_url and access_token above.
 # Can be the same daily channel or a separate admin/private channel.
-#MM_NOTIFY_ENABLED=true
-#MM_NOTIFY_CHANNEL_ID=your-notify-channel-id-here
+#   Set MM_NOTIFY_CHANNEL_ID in .env, then flip the toggle below.
+MM_NOTIFY_ENABLED=false
+MM_NOTIFY_CHANNEL_ID="${MM_NOTIFY_CHANNEL_ID:-}"
 
 # ── Credentials (.env override) ───────────────────────────────────────────────
 # Sensitive values (RTSP URLs with passwords, API tokens) can be kept out of