buds Phase 2: top-3 username|email autocomplete on #id_recipient (post share + my_buds add); implicit symmetric auto-add on share_post (sharer ↔ recipient buds graph); recipient field accepts username OR email — TDD

- billboard.views.search_buds(GET /billboard/buds/search?q=...) — top-3 prefix match against request.user.buds via Q(username__istartswith) | Q(email__istartswith). Returns {buds: [{id, username, email}]}. Privacy: only the user's own buds are searched, no leak of strangers.
  - _resolve_recipient(raw) helper resolves a free-form recipient (email if "@" present, else username, both case-insensitive). Wired into add_bud + share_post so #id_recipient accepts either form.
  - share_post implicit auto-add (per-spec): when recipient is registered + first-time-shared, both directions of buds M2M get the link — request.user.buds.add(recipient) AND recipient.buds.add(request.user). Idempotent, no auto-add on reshare/self/unregistered.
  - new bud-autocomplete.js shared module (apps/billboard/static/apps/billboard/) — bindBudAutocomplete(input, suggestionsEl, {searchUrl}). Mirrors sky.html birth-place picker: 250ms debounced fetch from MIN_CHARS=1, click-to-fill, Escape closes, click-outside closes, late-response drop. e.stopPropagation on suggestion-click so the bud-panel's outside-click handler doesn't fire and clear the input.
  - SCSS .bud-suggestions / .bud-suggestion-item mirrors .sky-suggestions but position:fixed bottom:4rem (aligned above the bud panel, with overflow:hidden on the panel forcing the dropdown to live as a sibling rather than a child). Landscape breakpoints clear the navbar/footer 4rem sidebars, 8rem at min-width 1800px.
  - both _bud_panel.html (post share) + _bud_add_panel.html (my_buds add) get the suggestions div sibling + script tags. Each panel's existing document click-outside handler now skips the suggestions container so a click inside doesn't close+clear. type="email" → type="text" since usernames are accepted; placeholder "friend@example.com or username".
  - new test classes in test_buds.py: SearchBudsViewTest (6 — prefix match, cap-3, email prefix, non-bud leakproof, empty-q, anon redirect) + SharePostImplicitAutoAddTest (4 — sharer.buds += recipient, recipient.buds += sharer, username-typed share, unregistered no-add) + AddBudViewTest.test_add_resolves_username_too. test_my_buds.py FT adds test_autocomplete_suggests_buds_by_username_prefix. test_sharing.py placeholder assertion updated to "friend@example.com or username".
  - 852 ITs (+11) + 5 my_buds FTs green.

Code architected by Disco DeDisco <discodedisco@outlook.com>
Git commit message Co-Authored-By:
Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/templates/apps/billboard/_partials/_bud_panel.html

@@ -19,12 +19,25 @@
      data-sharer-name="{% if request.user.is_authenticated %}{{ request.user|display_name }}{% endif %}">
     <input id="id_recipient"
            name="recipient"
-           type="email"
-           placeholder="friend@example.com"
+           type="text"
+           placeholder="friend@example.com or username"
            autocomplete="off">
     <button id="id_bud_ok" type="button" class="btn btn-confirm">OK</button>
 </div>
 
+{# Autocomplete suggestions — sibling of #id_bud_panel because the panel #}
+{# has overflow:hidden for its scaleX slide animation.                   #}
+<div id="id_bud_suggestions" class="bud-suggestions" hidden></div>
+
+<script src="{% static 'apps/billboard/bud-autocomplete.js' %}"></script>
+<script>
+    bindBudAutocomplete(
+        document.getElementById('id_recipient'),
+        document.getElementById('id_bud_suggestions'),
+        { searchUrl: '{% url "billboard:search_buds" %}' }
+    );
+</script>
+
 <script>
 (function () {
     'use strict';
@@ -73,6 +86,11 @@
         if (!html.classList.contains('bud-open')) return;
         if (panel.contains(e.target)) return;
         if (e.target === btn || btn.contains(e.target)) return;
+        // Autocomplete suggestions sit outside the panel (panel overflow
+        // is hidden for the scaleX slide). A click inside them must NOT
+        // close+clear the panel.
+        var sg = document.getElementById('id_bud_suggestions');
+        if (sg && sg.contains(e.target)) return;
         _close();
     });