chore(db): fix stale self-referencing numbers in migration header comments

Leftover from the 137/138 -> 142/143 renumber — the header comment and the
cross-reference to agentic_conversations still named the old numbers.

src/lib/db/migrations/142_agentic_conversations.sql

@@ -1,4 +1,4 @@
--- 137_agentic_conversations.sql
+-- 142_agentic_conversations.sql
 -- Stable multi-turn conversation tracking for /v1/chat/completions and
 -- /v1/responses. Clients resend the full growing message/input history on
 -- every turn; this table lets us detect "request N's history is request

src/lib/db/migrations/143_conversation_turn_nodes.sql

@@ -1,4 +1,4 @@
--- 138_conversation_turn_nodes.sql
+-- 143_conversation_turn_nodes.sql
 -- Per-turn hash-chain nodes backing a conversation's linear transcript
 -- (open-sse/services/conversationTracker.ts). Each row is one distinct
 -- turn instance, chained to its predecessor the same way a git commit
@@ -9,7 +9,7 @@
 -- duplicates a turn mid-history to keep provider-side prompt caches warm)
 -- becomes its OWN independent conversation instead (2026-08-06 — every
 -- OmniRoute conversation is a single straight line, it never forks; see
--- resolveConversationId's doc comment). See agentic_conversations (137) for
+-- resolveConversationId's doc comment). See agentic_conversations (142) for
 -- the conversation-root record; its last_message_count/last_messages_hash
 -- columns are superseded by this table and no longer written to.
 --