feat(config): ui width, auto exec, selection and navigation configs (#80)

closes #67

So I made an auto-exec confg `auto-exec = true`
(e32c0ba6ed69f3c764353e58b8fbacf160f37d5a) which means:
- If you want your command in the prompt to be executed right away, you
can set this = false (for example, you are typing `nvim ~/.conf` but
IRIS is suggesting `nvim ~/.config`, it will ignore the suggestion and
exec what you are typing, this is current default behavior)
- If you want to auto execute full command which is being suggested, you
can set this = true (this is the opposite of above, when you are typing
`nvim ~/.conf` but IRIS is suggesting `nvim ~/.config`, it will auto
exec `nvim ~/.config` instead, but sometime you want to exec what you
are typing instead of the suggestion right?, just press esc or shift tab
to hide the menu and it will)

---

Select keybinding to replace tab
(0dc01cba8c610e8d6fd8c50f6a71bdcc061a098f)
`select = "ctrl+y"`

Some users may love nvim keybinding or emacs, so I bring navigation
keybinding to be configurable (0dc01cba8c610e8d6fd8c50f6a71bdcc061a098f)
```
navigate-up = "ctrl+k"
navigate-down = "ctrl+j"
```
---

I also added a option for UI width
(dfa3b810a7be406fe4652b3886020f37bb166811)
`max-width = 80`
- If you configure `max-width` to be larger than the actual width of the
current terminal, Iris will automatically "compress" the window to match
the terminal's width (meaning it will never overflow and break the
interface)
- If you configure `max-width` too small (e.g 10), the interface will
have cramped text, making it look very bad. So, I've set a minimum safe
min limit of 40. If the configured value is smaller than this, Iris will
automatically use 40

Small note: If you set `max-width = 0` (or leave it blank), it will
automatically use Iris's default standard size of 76. SO you can
confidently customize it without fear of breaking the UI (I hope so
lmao)

---

Added a fallback to ensure Iris never crashes or loses shortcuts if the
user accidentally deletes keybinding configuration lines or
intentionally assigns empty strings " "
(f682c9bf623f3ed46ad0763221145604dbd91b07)

Fix typo `toggle_mode` to `toggle-mode`
(b39be6673e552735fa65a6c9807510c83b4d9cdd)

if you have a better config design, please tell me, I always listen to
your idea

root/init.go

@@ -235,6 +235,9 @@ debug = false
 # automatically expand aliases on space
 expand-alias = true
 
+# automatically execute command after accepting suggestion
+auto-execute = false
+
 [ui]
 # visual style: "modern" (icons, category pills, shortcut footer) or "classic" (minimalist, centered number, no icons)
 style = "modern"
@@ -254,6 +257,9 @@ max-suggestions = 100
 # maximum height of the overlay
 max-height = 15
 
+# maximum width of the overlay (0 = responsive to terminal)
+max-width = 0
+
 [git]
 # hide current branch in checkout/switch list
 filter-active-branch = true
@@ -272,10 +278,11 @@ channel = "stable"
 check-interval = "24h"
 
 [keybindings]
-toggle_mode = "ctrl+r"
-toggle_menu = "shift+tab"
-select_suggestion = "tab"
-accept_suggestion = "right"
+toggle-mode = "ctrl+r"
+toggle-menu = "shift+tab"
+select = "tab"
+navigate-up = "up"
+navigate-down = "down"
 `
 				if errWrite := os.WriteFile(path, []byte(defaultContent), 0644); errWrite == nil {
 					fmt.Printf("✓ Initialized default config file at %s\n", path)