fix: drop prefix_command from /poll and /remind

Multi-word String params can't be parsed by poise's whitespace-based
prefix parser without quoting, causing 'Too many arguments' on !poll
and !remind. Slash command already handles this correctly via
structured params, so prefix mode is dropped for these two.

src/feature/poll/command.rs

@@ -7,7 +7,7 @@ use serenity::all::{CreateEmbed, CreateEmbedFooter, ReactionType};
 const NUMBER_EMOJIS: [&str; 10] = ["1️⃣", "2️⃣", "3️⃣", "4️⃣", "5️⃣", "6️⃣", "7️⃣", "8️⃣", "9️⃣", "🔟"];
 
 /// `/poll <question> <options>` - options separated by `;` (2-10). Adds number reactions.
-#[poise::command(slash_command, prefix_command, guild_only)]
+#[poise::command(slash_command, guild_only)]
 pub async fn poll(
     ctx: Ctx<'_>,
     #[description = "Poll question"] question: String,

src/feature/remind/command.rs

@@ -19,7 +19,7 @@ fn parse_duration(input: &str) -> Option<u64> {
 }
 
 /// `/remind <duration> <message>` - e.g. `/remind 10m stretch break`. Max 7 days.
-#[poise::command(slash_command, prefix_command, guild_only)]
+#[poise::command(slash_command, guild_only)]
 pub async fn remind(
     ctx: Ctx<'_>,
     #[description = "Duration, e.g. 30s, 10m, 2h, 1d"] duration: String,