docs(readme): update TUI mockups to match actual code output

- Update browser and device flow diagrams to reflect actual rendering
- Remove non-existent outer border wrapping from TUI mockups
- Add step indicators and backoff warning to device flow diagram
- Correct header, spinner symbols, and help text to match code
- Remove messages not printed by current implementation

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: appleboy

README.md

@@ -173,46 +173,51 @@ The TUI provides:
 ### Browser Flow (Authorization Code + PKCE)
 
 ```
-╭─────────────────────────────────────────────────╮
-│ Authorization Code Flow with PKCE               │
-├─────────────────────────────────────────────────┤
-│                                                 │
-│ ● Step 1/3: Opening browser             ✓       │
-│ ● Step 2/3: Waiting for callback        ◐       │
-│ ○ Step 3/3: Exchanging tokens                   │
-│                                                 │
-│ Time remaining: 1:23 / 2:00                     │
-│ ▓▓▓▓▓▓▓▓▓▓▓▓░░░░░░░░░░░░░ 48%                   │
-│                                                 │
-│ ◐ Please complete authorization in your browser │
-│                                                 │
-│ Press Ctrl+C to cancel                          │
-╰─────────────────────────────────────────────────╯
+╭──────────────────────────────────────────────────╮
+│   Authorization Code Flow with PKCE              │
+╰──────────────────────────────────────────────────╯
+
+● Step 1/3: Opening browser           (green, completed)
+● Step 2/3: Waiting for callback      (purple, current)
+○ Step 3/3: Exchanging tokens         (gray, pending)
+
+Time remaining: 1:23 / 2:00
+████████████░░░░░░░░░░░░░ 48%
+
+⠙ Please complete authorization in your browser
+
+ctrl+c: cancel authentication • ?: toggle help
 ```
 
 ### Device Flow (Device Authorization Grant)
 
 ```
-╭─────────────────────────────────────────────────╮
-│ Device Authorization Grant Flow                 │
-├─────────────────────────────────────────────────┤
-│                                                 │
-│ ╔═══════════════════════════════════════════╗   │
-│ ║  Device Authorization                     ║   │
-│ ║                                           ║   │
-│ ║  Visit: https://auth.example.com/device   ║   │
-│ ║         ?user_code=ABCD-EFGH              ║   │
-│ ║                                           ║   │
-│ ║  Or go to: https://auth.example.com       ║   │
-│ ║  And enter: ABCD-EFGH                     ║   │
-│ ╚═══════════════════════════════════════════╝   │
-│                                                 │
-│ ◐ Waiting for authorization... (poll #8, 5s)    │
-│                                                 │
-│ Elapsed: 0:43                                   │
-│                                                 │
-│ Press Ctrl+C to cancel                          │
-╰─────────────────────────────────────────────────╯
+╭──────────────────────────────────────────────────╮
+│     Device Authorization Grant Flow              │
+╰──────────────────────────────────────────────────╯
+
+● Step 1/2: Requesting device code    (green, completed)
+● Step 2/2: Waiting for authorization (purple, current)
+
+╔══════════════════════════════════════════════════╗
+║  Device Authorization                            ║
+║                                                  ║
+║  Please authorize this device:                   ║
+║                                                  ║
+║  Visit: https://auth.example.com/device          ║
+║         ?user_code=ABCD-EFGH                     ║
+║                                                  ║
+║  Or go to: https://auth.example.com/device       ║
+║  And enter: ABCD-EFGH                            ║
+╚══════════════════════════════════════════════════╝
+
+⠙ Waiting for authorization... (poll #8, interval: 5s)
+
+⚠ Server requested slower polling: 5s → 10s
+
+Elapsed: 0:43
+
+ctrl+c: cancel authentication • ?: toggle help
 ```
 
 ### UI Mode Selection
@@ -292,7 +297,7 @@ Configuration is resolved in priority order: **CLI flag → environment variable
 Used when a local browser and a free callback port are available. Suitable for developer workstations.
 
 ```
-=== AuthGate CLI ===
+=== AuthGate Hybrid CLI (Browser + Device Code Flow) ===
 Client mode : public (PKCE)
 Server URL  : http://localhost:8080
 Client ID   : xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx
@@ -304,9 +309,7 @@ Step 1: Opening browser for authorization...
 
 Browser opened. Please complete authorization in your browser.
 Step 2: Waiting for callback on http://localhost:8888/callback ...
-Authorization code received!
 Step 3: Exchanging authorization code for tokens...
-Tokens saved to .authgate-tokens.json
 ```
 
 **Security properties:**
@@ -321,9 +324,10 @@ Tokens saved to .authgate-tokens.json
 Used when no browser is available: SSH sessions without display forwarding, Linux servers, CI environments.
 
 ```
-=== AuthGate CLI ===
+=== AuthGate Hybrid CLI (Browser + Device Code Flow) ===
 Auth method : Device Code Flow (SSH session without display forwarding)
 Step 1: Requesting device code...
+Step 2: Waiting for authorization...
 
 ----------------------------------------
 Please open this link to authorize:
@@ -333,9 +337,8 @@ Or visit : http://localhost:8080/device
 And enter: ABC-12345
 ----------------------------------------
 
-Step 2: Waiting for authorization...............
+.....
 Authorization successful!
-Tokens saved to .authgate-tokens.json
 ```
 
 **Polling behavior:**