🎨 Palette: Enhance anyhow nested error formatting in CLI

[ffalcinelli]

🎨 Palette: [Improve anyhow error formatting]

💡 What:
Updated src/main.rs to stop returning anyhow::Result<()> and instead return std::process::ExitCode. By doing this, we gain control over the Err match, allowing us to manually iterate through anyhow::Error::chain() using .enumerate().

🎯 Why:
By default, anyhow's Debug output for chained errors looks like a raw list:

Login failed

Caused by:
    0: Failed to send login request
    1: client error
    2: tcp connect error

Which is unintuitive for end users. The new format is much cleaner.

📸 Before/After:
Before:

Error: Login failed

Caused by:
    0: Failed to send login request
    1: client error
    2: tcp connect error
    3: Connection refused (os error 111)

After:

❌ Error:
  Login failed
    ↳ Failed to send login request
    ↳ client error
    ↳ tcp connect error
    ↳ Connection refused (os error 111)

♿ Ergonomics:
Errors are printed directly to stderr with appropriate ANSI color styling (via the console crate), improving readability while maintaining Unix piping standards. Evaluates strictly to ExitCode::FAILURE (1) upon error.

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PR created automatically by Jules for task 17220000211048694230 started by @ffalcinelli

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 96.01%. Comparing base (9777c21) to head (2ef12ae).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #169   +/-   ##
=======================================
  Coverage   96.01%   96.01%           
=======================================
  Files          29       29           
  Lines        2834     2834           
=======================================
  Hits         2721     2721           
  Misses        113      113           

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