feat: expand character editor to show all v2/v3 character card fields

Added support for all v2/v3 character card fields in the character editor UI:
- Description (10-row textarea)
- Scenario
- Message Example
- Post-History Instructions
- Alternate Greetings (one per line)
- Tags (comma-separated)
- Creator
- Character Version
- Creator Notes

Updated frontend to load and save all fields, and backend update_character
command to accept all new parameters. This allows imported v3 character cards
to display their full details, especially the description field which contains
the main character information.

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

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

src/index.html

@@ -184,6 +184,87 @@
               />
             </div>
 
+            <div class="form-group">
+              <label for="character-description">Description (Optional)</label>
+              <textarea
+                id="character-description"
+                placeholder="Detailed character description, appearance, background..."
+                rows="10"
+              ></textarea>
+            </div>
+
+            <div class="form-group">
+              <label for="character-scenario">Scenario (Optional)</label>
+              <textarea
+                id="character-scenario"
+                placeholder="The setting or situation where the character exists..."
+                rows="4"
+              ></textarea>
+            </div>
+
+            <div class="form-group">
+              <label for="character-mes-example">Message Example (Optional)</label>
+              <textarea
+                id="character-mes-example"
+                placeholder="Example dialogue from the character..."
+                rows="4"
+              ></textarea>
+            </div>
+
+            <div class="form-group">
+              <label for="character-post-history">Post-History Instructions (Optional)</label>
+              <textarea
+                id="character-post-history"
+                placeholder="Instructions to apply after chat history..."
+                rows="3"
+              ></textarea>
+            </div>
+
+            <div class="form-group">
+              <label for="character-alt-greetings">Alternate Greetings (Optional)</label>
+              <textarea
+                id="character-alt-greetings"
+                placeholder="One greeting per line..."
+                rows="3"
+              ></textarea>
+            </div>
+
+            <div class="form-group">
+              <label for="character-tags">Tags (Optional)</label>
+              <input
+                type="text"
+                id="character-tags"
+                placeholder="fantasy, adventure, comedy"
+              />
+            </div>
+
+            <div class="form-group">
+              <label for="character-creator">Creator (Optional)</label>
+              <input
+                type="text"
+                id="character-creator"
+                placeholder="Card creator name"
+              />
+            </div>
+
+            <div class="form-group">
+              <label for="character-version">Character Version (Optional)</label>
+              <input
+                type="text"
+                id="character-version"
+                placeholder="1.0"
+              />
+            </div>
+
+            <div class="form-group">
+              <label for="character-creator-notes">Creator Notes (Optional)</label>
+              <textarea
+                id="character-creator-notes"
+                placeholder="Notes from the creator..."
+                rows="2"
+              ></textarea>
+            </div>
+
             <div id="character-message" class="validation-message"></div>
 
             <button type="submit" id="save-character-btn" class="btn-primary">