feat(tmux): auto-name sessions with emoji + codename

- scripts/tmux-session-name.sh: generates random emoji + adj-noun name
  40 emojis x 40 adjectives x 40 nouns = 64,000 combinations
  Only renames numerically-named sessions (skips explicit names)

- tmux.conf.local: session-created hook calls the script automatically

- shell/common: added DOTFILES=$HOME/dotfiles env var so hooks and
  scripts can find the dotfiles root without hardcoded paths

Examples: '🐉 sonic-oracle', '🌟 electric-nebula', '🔱 nova-comet'

scripts/tmux-session-name.sh

@@ -0,0 +1,54 @@
+#!/usr/bin/env bash
+# tmux-session-name.sh — Auto-name new tmux sessions with emoji + codename
+#
+# Called by the session-created hook in .tmux.conf
+# Usage: tmux-session-name.sh <current_session_name> <session_id>
+
+CURRENT_NAME="${1:-}"
+SESSION_ID="${2:-}"
+
+# Skip if name is empty or not a plain number (user explicitly named it)
+if [[ -z "$CURRENT_NAME" || ! "$CURRENT_NAME" =~ ^[0-9]+$ ]]; then
+    exit 0
+fi
+
+# ── Name pool ─────────────────────────────────────────────────────────────────
+
+EMOJIS=(
+    "⚡" "🔥" "🌙" "🚀" "🎯" "💎" "🌊" "🎸" "🦊" "🐉"
+    "🌟" "🎭" "🔮" "🦋" "🌸" "🏔️" "🎪" "🦁" "🐺" "🦅"
+    "🐬" "🌋" "⚗️" "🧠" "🔭" "🎲" "🏹" "🌀" "🦄" "🐙"
+    "🎮" "🛸" "🌈" "🔱" "⚜️" "🧬" "🦾" "💫" "🎆" "🌌"
+)
+
+ADJECTIVES=(
+    swift blazing cosmic silent wild golden dark frozen epic neon
+    cyber ghost storm iron crystal hyper zen rogue nova apex
+    void shadow turbo lunar sonic electric primal ancient savage brave
+    mystic toxic ultra prime omega alpha delta sigma raging burning
+)
+
+NOUNS=(
+    wolf phoenix raven otter falcon dragon viper lynx shark cobra
+    titan spectre nexus cipher forge matrix pulse blade hawk panther
+    manta kraken hydra mantis raptor condor jaguar orca wraith banshee
+    golem oracle anvil tempest quasar nebula comet prism zenith apex
+)
+
+# ── Pick random combination ───────────────────────────────────────────────────
+
+# We use absolute arithmetic expansion to avoid negative index quirks
+EMOJI="${EMOJIS[$((RANDOM % ${#EMOJIS[@]}))]}"
+ADJ="${ADJECTIVES[$((RANDOM % ${#ADJECTIVES[@]}))]}"
+NOUN="${NOUNS[$((RANDOM % ${#NOUNS[@]}))]}"
+NEW_NAME="${EMOJI} ${ADJ}-${NOUN}"
+
+# ── Rename ────────────────────────────────────────────────────────────────────
+
+if [[ -n "$SESSION_ID" ]]; then
+    # Use -t with the specific session ID to avoid targeting the wrong session
+    tmux rename-session -t "$SESSION_ID" "$NEW_NAME" 2>/dev/null
+else
+    # Called standalone — just print the name
+    echo "$NEW_NAME"
+fi