feat: add configurable file upload limit via environment variable (#1080)

* fix: replace 6-word limit with 150-character limit for project names

Replaces the word-based validation with character-based validation
as originally requested in #971. The 6-word limit was causing issues
with small words and separators being counted equally, and didn't
match the original requirement for a character limit.

Changes:
- Backend: Replace wordCount validator with len validator (1-150 chars)
- Frontend: Replace word count validation with character length check
- UI already has line-clamp-3 for display truncation

Fixes #998

* fix: make password_digest migration compatible with all schema versions

Fixes a critical bug where the make-password-optional migration would silently
fail when upgrading from v1.0.0 or running on fresh v1.1.0-dev installations.

The migration was trying to SELECT columns (ai_provider, openai_api_key,
ollama_base_url, ollama_model) that don't exist in the users table at that
point in the migration chain, causing the INSERT...SELECT to fail and leaving
password_digest as NOT NULL. This prevented OIDC auto-provisioning from
creating new users without passwords.

The fix dynamically detects which columns exist in the users table using
PRAGMA table_info and only selects columns that are guaranteed to exist.
Missing columns (AI-related fields) will receive their default values from
the new table schema.

Changes:
- Added dynamic column detection using PRAGMA table_info
- Only SELECT columns that exist in the current users table
- AI columns get default values if they don't exist yet
- Applied same fix to both up and down migrations
- Properly handle password/password_digest column name migration

Fixes #1075

* feat: add configurable file upload limit via environment variable

Add FILE_UPLOAD_LIMIT_MB environment variable to make file upload limits configurable.
Previously hardcoded at 10MB, users can now customize this via Docker environment variables
or .env configuration to support larger file attachments.

Changes:
- Add FILE_UPLOAD_LIMIT_MB config with 10MB default fallback
- Update multer limits in tasks/attachments and projects routes
- Update Express body parser limits to use dynamic config
- Add /api/config endpoint to expose file limit to frontend
- Update frontend validation to fetch and use server config
- Add configService.ts for caching server configuration
- Update documentation with new environment variable

Fixes #1000

docs/00-tasks-behavior.md

@@ -157,7 +157,7 @@ This document explains how tasks work in tududi from a user behavior perspective
 
 22. **Tasks can have file attachments:**
     - Multiple files can be attached to a single task
-    - File size limit: 10MB per file
+    - File size limit: 10MB per file (configurable via `FILE_UPLOAD_LIMIT_MB` environment variable)
     - Stored in `/uploads/tasks/` directory
 
 23. **Allowed file types:**

docs/development-workflow.md

@@ -115,6 +115,7 @@ FRONTEND_URL=http://localhost:8080
 BACKEND_URL=http://localhost:3002
 PORT=3002
 HOST=0.0.0.0
+FILE_UPLOAD_LIMIT_MB=10
 
 # Optional - Email
 ENABLE_EMAIL=false