docs: add block/mute user relations, emoji-sync CLI, and uid indexes

- Add `/block`, `/mute` endpoints with block/unblock and mute/unmute functionality in `routers/relations.py`, hiding blocked users' content everywhere except their own profile while muting only suppresses notifications
- Introduce `devplace emoji-sync` CLI command to regenerate `static/js/emoji-shortcodes.js` from the emoji library, documented in `CLAUDE.md` and wired in `cli.py`
- Create `get_blocked_uids()` database helper and apply it in `content.py` `load_detail()` to filter blocked users' posts from detail views
- Implement `_uid_index()` and `_drop_index()` helpers in `database.py` for unique uid indexes across tables, with `user_relations` added to `SOFT_DELETE_TABLES`
- Document new routes in `AGENTS.md` and `README.md`, including emoji shortcodes rendering behavior distinct from the emoji picker

devplacepy/static/js/components/AppDialog.js

@@ -35,6 +35,11 @@ export class AppDialog extends Component {
         this.overlay = overlay;
         this.titleEl = overlay.querySelector(".dialog-title");
         this.messageEl = overlay.querySelector(".dialog-message");
+        const uid = Math.random().toString(36).slice(2, 9);
+        this.titleEl.id = `dialog-title-${uid}`;
+        this.messageEl.id = `dialog-message-${uid}`;
+        overlay.setAttribute("aria-labelledby", this.titleEl.id);
+        overlay.setAttribute("aria-describedby", this.messageEl.id);
         this.field = overlay.querySelector(".dialog-field");
         this.fieldLabel = overlay.querySelector(".dialog-field-label");
         this.input = overlay.querySelector(".dialog-input");
@@ -59,6 +64,24 @@ export class AppDialog extends Component {
                 this.dismiss();
             }
         });
+        overlay.addEventListener("keydown", (e) => {
+            if (e.key !== "Tab") return;
+            const items = [
+                ...overlay.querySelectorAll(
+                    'a[href], button:not([disabled]), input:not([disabled]), select, textarea, [tabindex]:not([tabindex="-1"])'
+                ),
+            ].filter((el) => el.offsetParent !== null);
+            if (!items.length) return;
+            const first = items[0];
+            const last = items[items.length - 1];
+            if (e.shiftKey && document.activeElement === first) {
+                e.preventDefault();
+                last.focus();
+            } else if (!e.shiftKey && document.activeElement === last) {
+                e.preventDefault();
+                first.focus();
+            }
+        });
     }
 
     open(mode, options) {