v0.8.0: TUI stabilization, command palette reverse-video highlight, hint bar redesign

- ROADMAP: consolidate all TUI work under v0.8.0 (removed premature
  v0.9.0/v0.10.x labels), restored original v0.9.0 eval harness plan
- channel-tui-view.org: Emacs-style reverse-video cursor (swap fg/bg
  instead of drawing █), hint bar now shows F:focus/MCP:count on left
  and token gauge + keybindings on right, sidebar reorganized to show
  GATE TRACE, RULES + BLOCK COUNT, COST, FILES panels
- channel-tui-main.org: command palette selection now uses reverse-video
  highlight (bg-input fg on input-fg bg, matching cursor style), fixed
  cond order so sel-p is checked before cat (all items had :category
  making sel-p unreachable), added session-cost extraction from daemon
- passepartout: export COLORTERM=truecolor for modern backend detection

lisp/security-vault.lisp

@@ -0,0 +1,86 @@
+(in-package :passepartout)
+
+(defvar *vault-memory* (make-hash-table :test 'equal)
+  "In-memory cache of sensitive credentials.")
+
+(defun vault-get (provider &key (type :api-key))
+  "Retrieves a credential from the vault or environment."
+  (let* ((key (format nil "~a-~a" provider type))
+         (val (gethash key *vault-memory*)))
+    (if val
+        val
+        (let ((env-var (case provider
+                          (:gemini "GEMINI_API_KEY")
+                          (:openai "OPENAI_API_KEY")
+                          (:anthropic "ANTHROPIC_API_KEY")
+                          (:openrouter "OPENROUTER_API_KEY")
+                          (otherwise nil))))
+          (when env-var (uiop:getenv env-var))))))
+
+(defun vault-set (provider secret &key (type :api-key))
+  "Stores a secret in the vault."
+  (let ((key (format nil "~a-~a" provider type)))
+    (setf (gethash key *vault-memory*) secret)))
+
+(defun vault-get-secret (provider)
+  "Retrieves a stored secret or token for a gateway provider."
+  (vault-get provider :type :secret))
+
+(defun vault-set-secret (provider secret)
+  "Stores a secret or token for a gateway provider."
+  (vault-set provider secret :type :secret))
+
+(defskill :passepartout-security-vault
+  :priority 600
+  :trigger (lambda (ctx) (declare (ignore ctx)) nil))
+
+(eval-when (:compile-toplevel :load-toplevel :execute)
+  (ql:quickload :fiveam :silent t))
+
+(defpackage :passepartout-security-vault-tests
+  (:use :cl :fiveam :passepartout)
+  (:export #:vault-suite))
+
+(in-package :passepartout-security-vault-tests)
+
+(def-suite vault-suite :description "Verification of the Credentials Vault")
+(in-suite vault-suite)
+
+(test test-vault-round-trip
+  "Contract 1: vault-set stores a value; vault-get retrieves it."
+  (let ((test-key :vault-test-round-trip)
+        (test-secret "secret-abc123"))
+    (vault-set test-key test-secret)
+    (is (string= test-secret (vault-get test-key)))
+    ;; Clean up
+    (vault-set test-key nil)))
+
+(test test-vault-missing-key
+  "Contract 2: vault-get returns NIL for an unset, unknown provider."
+  (is (null (vault-get :nonexistent-provider-xyz))))
+
+(test test-vault-isolation
+  "Contract 5: storing for provider A does not affect provider B."
+  (vault-set :vault-prov-a "secret-a")
+  (vault-set :vault-prov-b "secret-b")
+  (is (string= "secret-a" (vault-get :vault-prov-a)))
+  (is (string= "secret-b" (vault-get :vault-prov-b)))
+  (vault-set :vault-prov-a nil)
+  (vault-set :vault-prov-b nil))
+
+(test test-vault-secret-wrappers
+  "Contracts 3,4: vault-get-secret and vault-set-secret use :type :secret."
+  (let ((test-provider :vault-secret-test))
+    (vault-set-secret test-provider "my-token")
+    (is (string= "my-token" (vault-get-secret test-provider)))
+    ;; Clean up
+    (vault-set-secret test-provider nil)))
+
+(test test-vault-type-isolation
+  "Contract 5: different :type values produce different keys."
+  (vault-set :vault-type-test "key-value" :type :api-key)
+  (vault-set :vault-type-test "secret-value" :type :secret)
+  (is (string= "key-value" (vault-get :vault-type-test :type :api-key)))
+  (is (string= "secret-value" (vault-get :vault-type-test :type :secret)))
+  (vault-set :vault-type-test nil :type :api-key)
+  (vault-set :vault-type-test nil :type :secret))