Make One Dark's ansi.*magenta colors more magenta-y (#35423)

Tweak the `ansi.*magenta` colours so they are not confused with
`ansi.*red`. This matches how "One Light" behaves, where `ansi.*magenta`
uses the same purple as for keyword.

This change helps distinguish anything that the terminal might use
magenta for from errors, and helps make more readable the output of
certain tools.

For maintainers: The color for `ansi.magenta` is the same as for
`syntax.keyword`. The others are modifications on that colour to taste.
If you have some specific shades that need to be used please tell me, or
feel free to take over the PR.

Before: `jj log` and `difftastic` output

<img width="863" height="592" alt="Screenshot 2025-07-31 at 19 32 11"
src="https://github.com/user-attachments/assets/994b1cbd-ff64-4620-bd51-a5073fd6eb2a"
/>

After:

<img width="862" height="558" alt="Screenshot 2025-07-31 at 19 35 33"
src="https://github.com/user-attachments/assets/49dfb856-6b63-4498-8779-b8624230d6a3"
/>

Release Notes:

- N/A

---------

Co-authored-by: Danilo Leal <daniloleal09@gmail.com>

assets/themes/one/one.json

@@ -86,9 +86,9 @@
         "terminal.ansi.blue": "#74ade8ff",
         "terminal.ansi.bright_blue": "#385378ff",
         "terminal.ansi.dim_blue": "#bed5f4ff",
-        "terminal.ansi.magenta": "#be5046ff",
+        "terminal.ansi.magenta": "#b477cfff",
-        "terminal.ansi.bright_magenta": "#5e2b26ff",
+        "terminal.ansi.bright_magenta": "#d6b4e4ff",
-        "terminal.ansi.dim_magenta": "#e6a79eff",
+        "terminal.ansi.dim_magenta": "#612a79ff",
         "terminal.ansi.cyan": "#6eb4bfff",
         "terminal.ansi.bright_cyan": "#3a565bff",
         "terminal.ansi.dim_cyan": "#b9d9dfff",