refactor(home): move psql config out to the inventory

The postgresql client is installed from the private inventory, not this
baseline, so its dotfile config belongs there too. Drops `PSQLRC` and the
`psql/rc` history file; wget/readline stay (their tools are ubiquitous).

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

modules/home.nix

@@ -144,9 +144,8 @@ in
     # -p. Pins throwaway REPLs and new projects to one version across machines
     # (further steered by uv.toml below). Fetched on demand by uv, not Nix.
     UV_PYTHON = "3.14";
-    # psql / wget / readline configs, XDG-routed (the rc files are declared
-    # via xdg.configFile below).
-    PSQLRC = "${config.xdg.configHome}/psql/rc";
+    # wget / readline configs, XDG-routed (the rc files are declared via
+    # xdg.configFile below).
     WGETRC = "${config.xdg.configHome}/wget/wgetrc";
     INPUTRC = "${config.xdg.configHome}/readline/inputrc";
     # Rust/cargo: keep registry cache, git checkouts and `cargo install` bins
@@ -218,12 +217,6 @@ in
       python-preference = "managed"
     '';
 
-    # psql: unlimited, per-database history file (kept out of $HOME).
-    "psql/rc".text = ''
-      \set HISTFILE ${config.xdg.cacheHome}/psql/history-:DBNAME
-      \set HISTSIZE -1
-    '';
-
     # wget: keep its HSTS db in the cache dir, not ~/.
     "wget/wgetrc".text = ''
       hsts-file=${config.xdg.cacheHome}/wget/hsts