# Plan: Value Object Base Class

## Goal
Create a generic `Value[T]` base class in the framework layer. All value objects standardize on `.value` access via inheritance.

## Design

### `Value[T]` base class (`domain/framework/value.py`)
```python
@dataclass(frozen=True)
class Value(ABC, Generic[T]):
    value: T
```

- Frozen dataclass → immutability + structural equality (core Value Object semantics)
- `Generic[T]` → type-safe `.value` access in subclasses (e.g., `Value[str]`)
- `ABC` → mirrors the `Entity` pattern

### Subclasses
- `ClassifiedAdTitle(Value[str])` — drops `title: str`, inherits `value: T` bound to `str`
- `ClassifiedAdText(Value[str])` — drops `text: str`, inherits `value: T` bound to `str`

### Ripple effects
Every `.title` / `.text` reference on these objects becomes `.value`:
- `classified_ad.py` — `self.title.title` → `self.title.value`, construction calls, method bodies
- Tests — assertions, constructions, equality checks

## Files changed
| File | Change |
|------|--------|
| `domain/framework/value.py` | New — `Value[T]` base class |
| `domain/framework/__init__.py` | Add `Value` re-export |
| `domain/marketplace/classified_ad_title.py` | Inherit `Value[str]`, rename field |
| `domain/marketplace/classified_ad_text.py` | Inherit `Value[str]`, rename field |
| `domain/marketplace/classified_ad.py` | Update `.title`/`.text` refs → `.value` |
| `tests/test_classified_ad_title.py` | Update refs |
| `tests/test_classified_ad_text.py` | Update refs |
| `tests/test_classified_ad.py` | Update refs |

## Not in scope
`ClassifiedAdId`, `UserId`, `Money`, `Price` — stay as-is.

## Verification
- `pytest tests/` — all 63 tests pass
- `ruff check .` && `ruff format --check .` — clean