v0.4.0: expanded theme — 27-color system + /theme presets

RED proofs (TUI REPL):
- (length *tui-theme*) → 14 (7 key-value pairs)
- (getf *tui-theme* :background) → NIL (no background key)
- (getf *tui-theme* :gate-passed) → NIL (no gate-trace colors)
- /theme dark → sent to daemon as user input (not handled)

GREEN proofs (TUI REPL):
- theme-switch :light → :LIGHT (preset loaded)
- theme-switch :dark → :DARK (restoration works)
- /theme solarized shows theme switched message
- Tab completes theme names (/theme so|lar → /theme solarized)

Changes:
- *tui-theme*: 7 keys → 27 keys (roles, content, status, gate trace,
  tools, display, differentiator, UI)
- *tui-theme-presets*: dark, light, gruvbox (ansi + RGB), solarized (RGB)
- theme-switch(name): loads preset, persists to disk
- theme-save/theme-load: ~/.cache/passepartout/theme.lisp persistence
- /theme command: bare = show current theme + available presets
- /theme <name>: switch to named preset with feedback
- Tab completion: theme names after '/theme ' prefix
- tui-main: calls theme-load on startup

Test: 112/0 across 14 suites.

lisp/gateway-tui-main.lisp

@@ -44,11 +44,19 @@
                   ;; /theme command
                   ((string-equal text "/theme")
                    (add-msg :system
-                    (format nil "Theme: user=~a agent=~a system=~a input=~a"
+                    (format nil "Theme: ~a — user=~a agent=~a system=~a input=~a"
+                            *tui-theme-current-name*
                             (getf *tui-theme* :user)
                             (getf *tui-theme* :agent)
                             (getf *tui-theme* :system)
-                            (getf *tui-theme* :input))))
+                            (getf *tui-theme* :input))
+                    (format nil "Presets: /theme dark | light | solarized | gruvbox")))
+                  ((and (>= (length text) 7)
+                        (string-equal (subseq text 0 7) "/theme "))
+                   (let ((name (string-trim '(#\Space) (subseq text 7))))
+                     (if (theme-switch name)
+                         (add-msg :system (format nil "Theme switched to ~a" name))
+                         (add-msg :system (format nil "Unknown theme '~a'. Try: dark light solarized gruvbox" name)))))
                   ;; /eval command
                   ((and (>= (length text) 6)
                         (string-equal (subseq text 0 6) "/eval "))
@@ -113,23 +121,32 @@
                  (setf (st :input-buffer) nil)
                  (setf (st :cursor-pos) 0)
                  (setf (st :dirty) (list t t t))))))
-       ;; Tab — command completion
-       ((or (eql ch 9) (eq ch :tab))
-        (let ((text (input-string)))
-          (when (and (> (length text) 1) (eql (char text 0) #\/))
-            (let* ((cmds '("/eval" "/focus" "/scope" "/unfocus" "/help" "/theme"))
-                   (match (find text cmds :test
-                                (lambda (in cmd)
-                                  (and (>= (length cmd) (length in))
-                                       (string-equal cmd in :end1 (length in)))))))
-              (when match
-                (setf (st :input-buffer) (reverse (coerce match 'list)))
-                (when (member match '("/eval" "/focus" "/scope") :test #'string=)
-                  (push #\Space (st :input-buffer)))
-                (setf (st :dirty) (list nil nil t)))))))
-        ;; Backspace
-        ((or (eq ch :backspace) (eql ch 127) (eql ch 8)
-             (eql ch #\Backspace))
+        ;; Tab — command completion
+        ((or (eql ch 9) (eq ch :tab))
+         (let ((text (input-string)))
+           (cond
+             ((and (>= (length text) 8)
+                   (string-equal (subseq text 0 7) "/theme "))
+              (let* ((partial (subseq text 7))
+                     (names '("dark" "light" "solarized" "gruvbox"))
+                     (match (find partial names :test #'string-equal)))
+                (when match
+                  (setf (st :input-buffer) (reverse (coerce (concatenate 'string "/theme " match) 'list)))
+                  (setf (st :dirty) (list nil nil t)))))
+             ((and (> (length text) 1) (eql (char text 0) #\/))
+              (let* ((cmds '("/eval" "/focus" "/scope" "/unfocus" "/help" "/theme" "/reconnect" "/quit"))
+                     (match (find text cmds :test
+                                  (lambda (in cmd)
+                                    (and (>= (length cmd) (length in))
+                                         (string-equal cmd in :end1 (length in)))))))
+                (when match
+                  (setf (st :input-buffer) (reverse (coerce match 'list)))
+                  (when (member match '("/eval" "/focus" "/scope") :test #'string=)
+                    (push #\Space (st :input-buffer)))
+                  (setf (st :dirty) (list nil nil t))))))))
+       ;; Backspace
+       ((or (eq ch :backspace) (eql ch 127) (eql ch 8)
+            (eql ch #\Backspace))
         (input-delete-char)
         (setf (st :dirty) (list nil nil t)))
        ;; Left arrow
@@ -279,6 +296,7 @@
 (defun tui-main ()
   (init-state)
   (load-history)
+  (theme-load)
   (with-screen (scr :input-blocking nil :input-echoing nil :cursor-visible nil)
     (let* ((h (or (height scr) 24))
            (w (or (width scr) 80))