docs(desktop): design the minimal native desktop app (HACK-2214)

apps/desktop/diagrams/admin-handoff.mmd

@@ -0,0 +1,22 @@
+---
+title: Admin step · terminal hand-off
+---
+sequenceDiagram
+  autonumber
+  actor U as User
+  participant A as App
+  participant T as New terminal window
+  participant C as hack CLI
+  A->>U: Explain step, show exact command
+  alt Open Terminal (supported adapter)
+    U->>A: Open Terminal
+    A->>T: New window shows command, waits for Enter
+    U->>T: Enter
+    T->>C: hack global trust
+    C->>U: sudo asks for password (in the terminal)
+  else Copy command
+    U->>A: Copy, run it anywhere
+  end
+  U->>A: Check again
+  A->>C: read-only check
+  A->>U: Done, still needed, or unknown

apps/desktop/diagrams/always-on.mmd

@@ -0,0 +1,28 @@
+---
+title: Always-on · one project
+---
+stateDiagram-v2
+  direction TB
+  [*] --> Off
+  Off --> On : switch on ok
+  On --> Off : switch off ok
+  On --> Paused : manual Stop
+  Paused --> On : manual Start
+  Paused --> Off : switch off
+  On --> NeedsAttention : max failures
+  NeedsAttention --> On : Retry ok
+  NeedsAttention --> Off : switch off
+  note right of Off
+    INV a failed autostart command
+    leaves the switch where it was
+  end note
+  note right of On
+    INV global pause holds every
+    project without changing it
+  end note
+  classDef live stroke-width:1.6px
+  classDef wait stroke-dasharray:2 2
+  classDef fail stroke-width:2px
+  class On live
+  class Paused wait
+  class NeedsAttention fail