Merge #126: Add Theme/Configuration Support for UserOutput

2835384 feat: [#124] export Theme in presentation module public API (copilot-swe-agent[bot])
03bdca4 fix: [#124] address clippy warnings and apply rustfmt (copilot-swe-agent[bot])
e68b452 feat: [#124] add Theme struct with emoji, plain, and ASCII variants (copilot-swe-agent[bot])
7a27a23 Initial plan (copilot-swe-agent[bot])

Pull request description:

  Extracts hardcoded emoji symbols from `UserOutput` methods into a configurable `Theme` struct, enabling support for different output styles (emoji, plain text, ASCII) based on environment or user preferences.

  ## Changes

  **Theme System**
  - Added `Theme` struct with three predefined themes:
    - `emoji()` - Unicode symbols (⏳ ✅ ⚠️ ❌) for interactive terminals (default)
    - `plain()` - Text labels ([INFO] [OK] [WARN] [ERROR]) for CI/CD pipelines
    - `ascii()` - ASCII characters (=> [+] [!] [x]) for limited terminal support
  - Implements `Default` trait returning emoji theme for backward compatibility

  **UserOutput Integration**
  - Added `theme: Theme` field to `UserOutput`
  - Added `UserOutput::with_theme(verbosity, theme)` constructor
  - Updated all output methods (`progress()`, `success()`, `warn()`, `error()`) to use `self.theme.X_symbol()`
  - Removed hardcoded symbols from method implementations

  **Testing**
  - Added `TestUserOutput::with_theme()` for theme injection in tests
  - 11 new tests covering theme creation, accessors, and integration

  ## Usage

  ```rust
  use torrust_tracker_deployer_lib::presentation::user_output::{UserOutput, VerbosityLevel, Theme};

  // Default emoji theme (existing behavior)
  let mut output = UserOutput::new(VerbosityLevel::Normal);

  // Plain text for CI/CD
  let mut output = UserOutput::with_theme(VerbosityLevel::Normal, Theme::plain());
  output.success("Deployment complete"); // [OK] Deployment complete

  // ASCII for limited terminals
  let mut output = UserOutput::with_theme(VerbosityLevel::Normal, Theme::ascii());
  output.success("Deployment complete"); // [+] Deployment complete
  ```

  All existing code continues to work without modifications.

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  <details>

  <summary>Original prompt</summary>

  >
  > ----
  >
  > *This section details on the original issue you should resolve*
  >
  > <issue_title>Add Theme/Configuration Support for UserOutput</issue_title>
  > <issue_description>## Overview
  >
  > Extract emoji symbols from `UserOutput` methods into a configurable `Theme` struct. This enables support for different output styles (emoji, plain text, ASCII) based on environment or user preferences, making the application more accessible and CI/CD-friendly.
  >
  > ## Specification
  >
  > See detailed specification: [docs/issues/124-add-theme-configuration-support.md](https://github.com/torrust/torrust-tracker-deployer/blob/main/docs/issues/124-add-theme-configuration-support.md)
  >
  > ## 🏗️ Architecture Requirements
  >
  > **DDD Layer**: Presentation
  > **Module Path**: `src/presentation/user_output.rs`
  > **Pattern**: Configuration/Theme Pattern
  >
  > ### Module Structure Requirements
  >
  > - [ ] Create `Theme` struct within `user_output.rs` module
  > - [ ] Implement predefined theme constructors (`emoji()`, `plain()`, `ascii()`)
  > - [ ] Implement `Default` trait for `Theme` (emoji theme)
  > - [ ] Update `UserOutput` to use `Theme` for all symbol formatting
  > - [ ] Follow module organization conventions (see [docs/contributing/module-organization.md](https://github.com/torrust/torrust-tracker-deployer/blob/main/docs/contributing/module-organization.md))
  >
  > ### Architectural Constraints
  >
  > - [ ] **No breaking changes**: Existing code using default constructor continues to work
  > - [ ] **Backward compatibility**: Default theme uses emoji (current behavior)
  > - [ ] **Extensibility**: Easy to add new themes without modifying output methods
  > - [ ] **Type safety**: Theme fields are strongly typed
  > - [ ] **Immutability**: Theme is set at construction, not modified during runtime
  >
  > ### Anti-Patterns to Avoid
  >
  > - ❌ **Global mutable theme** - Don't use static mutable for theme configuration
  > - ❌ **Runtime theme switching** - Theme is set at construction, not changed afterward
  > - ❌ **Hardcoded symbols in methods** - All symbols must come from `Theme`
  >
  > ## Implementation Plan
  >
  > ### Phase 1: Create Theme Struct (1-2 hours)
  >
  > - [ ] Create `Theme` struct with symbol fields
  > - [ ] Implement `Theme::emoji()`, `Theme::plain()`, `Theme::ascii()`
  > - [ ] Implement accessor methods and `Default` trait
  > - [ ] Add comprehensive documentation
  >
  > ### Phase 2: Add Unit Tests for Theme (1 hour)
  >
  > - [ ] Test all predefined themes
  > - [ ] Test accessor methods
  > - [ ] Test theme cloning and equality
  >
  > ### Phase 3: Integrate Theme into UserOutput (2-3 hours)
  >
  > - [ ] Add `theme: Theme` field to `UserOutput`
  > - [ ] Create `UserOutput::with_theme()` constructor
  > - [ ] Update all output methods to use `self.theme.X_symbol()`
  > - [ ] Remove hardcoded symbols
  >
  > ### Phase 4: Update Tests (2-3 hours)
  >
  > - [ ] Update test infrastructure to support themes
  > - [ ] Add tests for each theme variant
  > - [ ] Verify all existing tests pass
  >
  > ### Phase 5: Documentation and Verification (1 hour)
  >
  > - [ ] Add module documentation
  > - [ ] Add usage examples
  > - [ ] Run pre-commit checks: `./scripts/pre-commit.sh`
  >
  > ## Acceptance Criteria
  >
  > > **Note for Contributors**: These criteria define what the PR reviewer will check. Use this as your pre-review checklist before submitting the PR to minimize back-and-forth iterations.
  >
  > **Quality Checks**:
  >
  > - [ ] Pre-commit checks pass: `./scripts/pre-commit.sh`
  >
  > **Theme Implementation Checks**:
  >
  > - [ ] `Theme` struct exists with all symbol fields
  > - [ ] All predefined themes implemented: `emoji()`, `plain()`, `ascii()`
  > - [ ] `Default` trait returns emoji theme
  > - [ ] All accessor methods implemented
  >
  > **Integration Checks**:
  >
  > - [ ] `UserOutput` has `theme: Theme` field
  > - [ ] `UserOutput::with_theme()` constructor exists
  > - [ ] All output methods use theme symbols (no hardcoded symbols)
  >
  > **Testing Checks**:
  >
  > - [ ] Theme unit tests cover all variants
  > - [ ] Test infrastructure supports theme injection
  > - [ ] All existing tests pass
  >
  > **Backward Compatibility Checks**:
  >
  > - [ ] Default `UserOutput::new()` uses emoji theme
  > - [ ] No breaking changes to public API
  >
  > **Documentation Checks**:
  >
  > - [ ] Theme system fully documented
  > - [ ] Usage examples for each theme
  > - [ ] Each theme variant documented with use case
  >
  > ## Related
  >
  > - Parent: #102 (Epic: User Output Architecture Improvements)
  > - Roadmap: N/A (Code quality improvement)
  > - Specification: [docs/issues/124-add-theme-configuration-support.md](https://github.com/torrust/torrust-tracker-deployer/blob/main/docs/issues/124-add-theme-configuration-support.md)</issue_description>
  >
  > ## Comments on the Issue (you are @copilot in this section)
  >
  > <comments>
  > </comments>
  >

  </details>

  - Fixes #124

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ACKs for top commit:
  josecelano:
    ACK 2835384

Tree-SHA512: 46e0fddbf33edc5622ccc01a226d1a44d57fd1b45f9797304a1082f41741bc00dc6ffbd890d96c85ac918de9ac3c4684d89176bd9d49ee81b0088d4e140c286a

Author: josecelano

src/presentation/mod.rs

@@ -51,4 +51,4 @@ pub use commands::destroy::DestroySubcommandError;
 pub use commands::{execute, handle_error};
 pub use errors::CommandError;
 pub use progress::ProgressReporter;
-pub use user_output::{UserOutput, VerbosityLevel};
+pub use user_output::{Theme, UserOutput, VerbosityLevel};