feat: adopt per-bot account api key for gateway attribution and improve post distinctness

- Add `account_api_key` field to `BotState` and `_adopt_account_api_key()` method that fetches the bot's own `users.api_key` from its profile JSON after auth, switching `LLMClient` to use it instead of the shared bootstrap key, routing gateway spend through the bot's user identity
- Replace `interleave_by_author` with a simpler greedy algorithm that picks the first row whose owner differs from the last picked, removing the multi-queue priority logic
- Extend `_ai_quota` response with `unlimited`, `requests`, and `last_used` fields sourced from new `user_spend_24h()` analytics helper
- Pass `recent_post_titles` from `BotState` into `LLMClient.generate_post()` and add a `distinct_rule` prompt instructing the model to avoid repeating framing, examples, or opinions from the bot's last six posts
- Remove early-return dedup check in `ArticleRegistry.admit` that skipped articles already held by the same bot owner, allowing re-admission under a different category
- Render bot username as a clickable link with avatar in the admin bots table

tests/e2e/post.py

@@ -28,6 +28,22 @@ def test_post_detail_page(alice):
     assert page.is_visible("text=Back to Feed")
 
 
+def test_create_post_modal_targets_modal_textarea_on_populated_feed(alice):
+    page, _ = alice
+    create_post(page, "devlog", "Seed post so the feed renders comment forms")
+    page.goto(f"{BASE_URL}/feed", wait_until="domcontentloaded")
+    page.locator(".feed-fab").first.wait_for(state="visible", timeout=10000)
+    assert page.locator("textarea[name='content']").count() > 1
+    page.locator(".feed-fab").first.click()
+    modal_content = page.locator("#create-post-modal textarea[name='content']")
+    modal_content.wait_for(state="visible", timeout=10000)
+    modal_content.click()
+    modal_content.fill("Modal scoped body well over ten characters long.")
+    page.locator("#create-post-modal button.btn-primary:has-text('Post')").click()
+    page.wait_for_url(f"{BASE_URL}/posts/*", wait_until="domcontentloaded")
+    assert page.is_visible("text=Modal scoped body well over ten characters long.")
+
+
 def test_post_topic_badge(alice):
     page, _ = alice
     create_post(page, "question", "Question post for badge check")