refactor(backend): clean up jail service, add error handling service

- Extract jail status/processing to helper functions
- Add error_handling.py service for centralized error handling
- Update config.py with validation and defaults
- Update .env.example with all config options
- Remove obsolete Tasks.md, add Service-Development.md
- Minor fixes across routers and services

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Docs/Tasks.md

@@ -1,81 +1,3 @@
-### Issue #25: MEDIUM - Incomplete Type Hints in Error Handling
-
-**Where found**: 
-- `backend/app/main.py` (line 283)
-- Error metadata uses `dict[str, str | int | list[str]]` instead of TypedDict
-
-**Why this is needed**: 
-Generic types don't enable proper type narrowing in exception handlers. Code can't safely access error fields.
-
-**Goal**: 
-Use TypedDict for type-safe error responses.
-
-**What to do**:
-1. Define error response types:
-   ```python
-   class ErrorResponse(TypedDict):
-       error_id: str
-       timestamp: int
-       message: str
-       tracebacks: list[str]
-       correlation_id: str
-   ```
-2. Use in exception handlers
-3. Type checker can verify correct field access
-
-**Possible traps and issues**:
-- TypedDict is Python 3.8+ only
-- Need to maintain multiple error response types
-
-**Docs changes needed**:
-- Add type safety guidelines
-
-**Doc references**:
-- DETAILED_FINDINGS.md - Issue #21 "Incomplete Type Hints"
-
----
-
-### Issue #26: MEDIUM - Hardcoded Constants Not Configurable
-
-**Where found**: 
-- `backend/app/utils/constants.py`
-- MAX_PAGE_SIZE = 1000
-- BLOCKLIST_PREVIEW_MAX_LINES = 100
-- HISTORY_RETENTION_DAYS = 90
-
-**Why this is needed**: 
-Different deployments have different needs:
-- Large deployment might want smaller pages
-- User might want different preview size
-- Some want longer history retention
-
-**Goal**: 
-Make limits configurable via environment variables.
-
-**What to do**:
-1. Move constants to config:
-   ```python
-   class Settings(BaseSettings):
-       max_page_size: int = Field(default=1000, env="BANGUI_MAX_PAGE_SIZE")
-       blocklist_preview_max_lines: int = Field(default=100, env="BANGUI_PREVIEW_MAX_LINES")
-       history_retention_days: int = Field(default=90, env="BANGUI_HISTORY_RETENTION")
-   ```
-2. Validate ranges (max_page_size > 0, < 10000)
-3. Update .env.example with all options
-4. Document in configuration guide
-
-**Possible traps and issues**:
-- Too many configuration options can be overwhelming
-- Some limits have dependencies (page_size < max_records)
-
-**Docs changes needed**:
-- Add to configuration reference
-
-**Doc references**:
-- DETAILED_FINDINGS.md - Issue #20 "Hardcoded Constants"
-
----
-
 ### Issue #27: MEDIUM - Inconsistent Error Handling Patterns
 
 **Where found**: