fix(session): merge-time fixes for #491

- claude watchingLine: the lookahead keys on "Artifact" alone, so a
  footer truncated mid-chip ("1 Artifact…", "1 Artifact comm…") is still
  refused instead of reporting the shell beside it; comment follows
- test: both truncations return no watching label
- invariants: a chip that waits on a human never counts as watching, and
  the ^ anchor is what stops the retry past the chip

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

src/config/cli-registry/stock.ts

@@ -242,10 +242,11 @@ const CLAUDE: CliEntry = {
       // lookahead refuses the whole row while that chip is on it, whatever else is
       // running beside it. The `^` is what makes the lookahead judge the row once:
       // without it the engine retries from each later position, and a start past the
-      // chip reports the shell beside it. The lookahead stops short of "monitor", so a
-      // footer cut off mid-chip still counts. Counting the chip as watching kept the
+      // chip reports the shell beside it. The lookahead keys on "Artifact" alone, so a
+      // footer cut off mid-chip (`· 1 Artifact…`, `· 1 Artifact comm…`) is still refused;
+      // no other chip on this row says "Artifact". Counting the chip as watching kept the
       // idle alert quiet for a session that was waiting for a human.
-      watchingLine: String.raw`^(?!.*Artifact comment).*?·\s*(\d+ (?:monitors?|shells?|teams?|local agents?|cloud sessions?|MCP tasks?|background tasks?|(?:background|remote) dynamic workflows?))`,
+      watchingLine: String.raw`^(?!.*Artifact).*?·\s*(\d+ (?:monitors?|shells?|teams?|local agents?|cloud sessions?|MCP tasks?|background tasks?|(?:background|remote) dynamic workflows?))`,
       // When a turn ends while background agents or an ultracode workflow are still
       // running, Claude swaps its `✻ Brewed for 1m 18s` closing row for
       // `✻ Waiting for 2 background agents and 1 dynamic workflow to finish` and resumes