Add NSFW-only filtering mode for content moderation

- Add nsfw_only_filtering field to GuildSettings model
- Create database migration for new field (20260124_add_nsfw_only_filtering)
- Update AI moderation logic to respect NSFW-only mode
- Add Discord command !ai nsfwonly <true/false> for toggling mode
- Implement filtering logic in image analysis for both attachments and embeds
- Add comprehensive test suite for new functionality
- Update documentation with usage examples and feature description
- Create dedicated CI workflow for testing NSFW-only filtering feature

When enabled, only sexual/nude content is filtered while allowing:
- Violence and gore
- Harassment and bullying
- Hate speech
- Self-harm content
- Other content categories

This mode is useful for gaming communities and mature discussion
servers that have specific content policies allowing violence
but prohibiting sexual material.

README.md

@@ -19,6 +19,7 @@ GuardDen is a comprehensive Discord moderation bot designed to protect your comm
 ### AI Moderation
 - **Text Analysis** - AI-powered content moderation using Claude or GPT
 - **NSFW Image Detection** - Automatic flagging of inappropriate images
+- **NSFW-Only Filtering** - Option to only filter sexual content, allowing violence/harassment
 - **Phishing Analysis** - AI-enhanced detection of scam URLs
 - **Configurable Sensitivity** - Adjust strictness per server (0-100)
 
@@ -177,7 +178,7 @@ Each server can configure:
 - Automod toggles (spam, links, banned words)
 - Automod thresholds and scam allowlist
 - Strike action thresholds
-- AI moderation settings (enabled, sensitivity, confidence threshold, log-only, NSFW detection)
+- AI moderation settings (enabled, sensitivity, confidence threshold, log-only, NSFW detection, NSFW-only mode)
 - Verification settings (type, enabled)
 
 ## Commands
@@ -245,6 +246,7 @@ Managed wordlists are synced weekly by default. You can override sources with
 | `!ai threshold <0.0-1.0>` | Set AI confidence threshold |
 | `!ai logonly <true/false>` | Toggle AI log-only mode |
 | `!ai nsfw <true/false>` | Toggle NSFW image detection |
+| `!ai nsfwonly <true/false>` | Toggle NSFW-only filtering mode |
 | `!ai analyze <text>` | Test AI analysis on text |
 
 ### Diagnostics (Admin only)
@@ -386,6 +388,23 @@ The AI analyzes content for:
 3. Actions are taken based on guild sensitivity settings
 4. All AI actions are logged to the mod log channel
 
+### NSFW-Only Filtering Mode
+
+For communities that only want to filter sexual content while allowing other content types:
+
+```
+!ai nsfwonly true
+```
+
+**When enabled:**
+- ✅ **Blocked:** Sexual content, nude images, explicit material
+- ❌ **Allowed:** Violence, harassment, hate speech, self-harm content
+
+**When disabled (normal mode):**
+- ✅ **Blocked:** All inappropriate content categories
+
+This mode is useful for gaming communities, mature discussion servers, or communities with specific content policies that allow violence but prohibit sexual material.
+
 ## Development
 
 ### Running Tests