dotfiles: initial scaffold for Coder devboxes

install.sh (symlink home/* + merge-seed ~/.claude.json onboarding), gitconfig,
bash_aliases, global gitignore, inputrc, tmux.conf. Golden owns tools+starship;
this owns personal config. Secrets stay in Coder user-secrets.

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

install.sh

@@ -0,0 +1,41 @@
+#!/usr/bin/env bash
+# Coder dotfiles bootstrap — runs via `coder dotfiles` on every workspace start.
+# Idempotent + merge-safe. Golden owns system tools + starship/mise/eza; this repo
+# owns personal config only. Safe to run repeatedly.
+set -euo pipefail
+DOTS="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+log(){ printf '[dotfiles] %s\n' "$*"; }
+
+# 1) Symlink everything under home/ into $HOME, preserving structure. A real
+#    (non-symlink) file already there is backed up once to <file>.pre-dotfiles.
+if [ -d "$DOTS/home" ]; then
+  while IFS= read -r -d '' f; do
+    rel="${f#"$DOTS/home/"}"
+    dst="$HOME/$rel"
+    mkdir -p "$(dirname "$dst")"
+    if [ -e "$dst" ] && [ ! -L "$dst" ]; then mv "$dst" "$dst.pre-dotfiles"; fi
+    ln -sfn "$f" "$dst"
+    log "linked ~/$rel"
+  done < <(find "$DOTS/home" -type f -print0)
+fi
+
+# 2) Seed ~/.claude.json so Claude Code skips first-run onboarding (theme + login
+#    wizard). Auth itself comes from the CLAUDE_CODE_OAUTH_TOKEN user-secret env
+#    var — this only marks onboarding complete. Merge-safe: preserves whatever
+#    Claude Code writes there (projects, mcp, etc.).
+if command -v python3 >/dev/null 2>&1; then
+  python3 - <<'PY'
+import json, os
+p = os.path.expanduser("~/.claude.json")
+try:
+    d = json.load(open(p))
+except Exception:
+    d = {}
+d.setdefault("theme", "dark")
+d["hasCompletedOnboarding"] = True
+json.dump(d, open(p, "w"), indent=2)
+print("[dotfiles] seeded ~/.claude.json (onboarding + theme)")
+PY
+fi
+
+log "done"