Restructure project and add user settings persistence

- Move src/clide/ to clide/ (flatten directory structure)
- Add SettingsService for persistent user preferences
- Settings stored in ~/.clide/settings.json
- Persist theme, panel visibility, and compact mode state
- Fix terminal rendering glitch with throttled refresh (~60fps)
- Update pyproject.toml, Makefile, and tests for new structure

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

clide/models/editor.py

@@ -0,0 +1,72 @@
+"""Editor-related Pydantic models."""
+
+from pathlib import Path
+
+from pydantic import BaseModel, ConfigDict
+
+
+class CursorPosition(BaseModel):
+    """Cursor position in editor."""
+
+    model_config = ConfigDict(strict=True, frozen=True)
+
+    line: int
+    column: int
+
+
+class Selection(BaseModel):
+    """Text selection range."""
+
+    model_config = ConfigDict(strict=True, frozen=True)
+
+    start: CursorPosition
+    end: CursorPosition
+
+
+class FileBuffer(BaseModel):
+    """A file buffer in the editor."""
+
+    model_config = ConfigDict(strict=True)
+
+    path: Path
+    content: str
+    language: str | None = None
+    is_modified: bool = False
+    cursor: CursorPosition = CursorPosition(line=0, column=0)
+    selection: Selection | None = None
+    scroll_offset: int = 0
+
+    @property
+    def filename(self) -> str:
+        """Get the filename from path."""
+        return self.path.name
+
+    @property
+    def display_name(self) -> str:
+        """Get display name with modification indicator."""
+        prefix = "● " if self.is_modified else ""
+        return f"{prefix}{self.filename}"
+
+
+class EditorState(BaseModel):
+    """State of the editor panel."""
+
+    model_config = ConfigDict(strict=True)
+
+    buffers: list[FileBuffer] = []
+    active_buffer_index: int | None = None
+    recent_files: list[Path] = []
+
+    @property
+    def active_buffer(self) -> FileBuffer | None:
+        """Get currently active buffer."""
+        if self.active_buffer_index is not None and self.buffers:
+            return self.buffers[self.active_buffer_index]
+        return None
+
+    def get_buffer_by_path(self, path: Path) -> FileBuffer | None:
+        """Find a buffer by its file path."""
+        for buffer in self.buffers:
+            if buffer.path == path:
+                return buffer
+        return None