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/unit/services/openai_gateway/analytics.py

@@ -148,6 +148,7 @@ def test_ai_quota_percentage_and_clamp(local_db):
     set_setting("devii_user_daily_usd", "2.0")
     try:
         half, _, _ = _make_user_ai_usage_profile()
+        _seed_gateway(half, n=2, cost=0.5)
         get_table("devii_usage_ledger").insert(
             {
                 "owner_kind": "user",
@@ -159,18 +160,11 @@ def test_ai_quota_percentage_and_clamp(local_db):
         quota = _ai_quota(half)
         assert quota is not None
         assert quota["used_pct"] == 50.0
+        assert quota["requests"] == 2
         assert quota["turns"] == 1
 
         over, _, _ = _make_user_ai_usage_profile()
-        for _ in range(3):
-            get_table("devii_usage_ledger").insert(
-                {
-                    "owner_kind": "user",
-                    "owner_id": over,
-                    "created_at": _now_iso_ai_usage_profile(),
-                    "cost_usd": 1.0,
-                }
-            )
+        _seed_gateway(over, n=3, cost=1.0)
         capped = _ai_quota(over)
         assert capped["used_pct"] == 100.0
     finally: