refactor: Standardize error handling patterns across codebase

Comprehensive error handling improvements addressing inconsistent patterns:

• Created markitect/exceptions.py with complete domain-specific exception hierarchy
  - MarkitectError base class with context and cause chaining support
  - Specific exceptions for Document, AST, Cache, Database, Schema operations
  - Built-in logging and context preservation

• Fixed overly broad exception handling in tddai modules:
  - issue_fetcher.py: Replace generic Exception with specific Gitea errors
  - project_manager.py: Proper error translation with context preservation
  - coverage_analyzer.py: Replace silent suppression with logging

• Enhanced cache_service.py error handling:
  - Specific OSError/PermissionError handling for file operations
  - Logging integration for unexpected errors
  - Preserved error collection and reporting

• Implemented proper exception chaining patterns:
  - All error translations use `raise ... from e` for debugging
  - Preserved original exception context and stack traces
  - Added docstring declarations of raised exceptions

• Benefits:
  - Eliminates silent error suppression and debugging black holes
  - Provides specific, actionable error messages
  - Preserves full error context for troubleshooting
  - Establishes consistent patterns for future development

Resolves issue #21: Error handling standardization

🤖 Generated with [Claude Code](https://claude.ai/code)

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

tddai/project_manager.py

@@ -10,6 +10,7 @@ from typing import Dict, Any, List, Optional
 
 from gitea import GiteaClient, GiteaConfig
 from gitea.models import ProjectState, Priority, Milestone as GiteaMilestone, Label as GiteaLabel
+from gitea.exceptions import GiteaError, GiteaNotFoundError, GiteaAuthError, GiteaApiError
 from .config import get_config
 from .exceptions import IssueError
 
@@ -32,7 +33,16 @@ class ProjectManager:
         self.gitea_client = GiteaClient(gitea_config)
 
     def _make_api_call(self, method: str, url: str, data: Dict[str, Any] = None) -> Dict[str, Any]:
-        """Make authenticated API call to Gitea (kept for backwards compatibility)."""
+        """Make authenticated API call to Gitea (kept for backwards compatibility).
+
+        Args:
+            method: HTTP method (GET, POST, etc.)
+            url: API endpoint URL
+            data: Optional request data
+
+        Raises:
+            IssueError: When API call fails (with specific context)
+        """
         # This method is kept for backwards compatibility but now delegates to the gitea client
         # For new code, use the gitea_client directly
         try:
@@ -45,8 +55,16 @@ class ProjectManager:
                 return self._issue_to_dict(issue)
             else:
                 raise IssueError(f"Legacy API call not supported: {method} {url}")
-        except Exception as e:
-            raise IssueError(f"API call failed: {e}")
+        except GiteaNotFoundError as e:
+            raise IssueError(f"Resource not found for {method} {url}") from e
+        except GiteaAuthError as e:
+            raise IssueError(f"Authentication failed for {method} {url}") from e
+        except GiteaApiError as e:
+            raise IssueError(f"API error for {method} {url}: {e}") from e
+        except GiteaError as e:
+            raise IssueError(f"Gitea error for {method} {url}: {e}") from e
+        except (ValueError, IndexError) as e:
+            raise IssueError(f"Invalid URL format for {method} {url}") from e
 
     def _issue_to_dict(self, issue) -> Dict[str, Any]:
         """Convert Issue object to dict for backwards compatibility."""