feat: auto-compact and auto-clear from the statusLine context size

Both checks compared getTotalTokens() against the threshold. That
counter leaves out cache reads, so it stays far below the real context,
and the 500k cap ruled out thresholds on a 1M window.

POST /api/status-telemetry now hands context_window.total_input_tokens
and context_window_size to Session.noteContextReport(), which runs both
checks. The decision is a pure function, decideAutoThreshold(). The
counter stays the fallback when no report has arrived.

After a /compact or /clear the pre-command report is ignored by value,
since it stays the newest number until the command finishes. The first
differing report came later, so a swallowed command fires again instead
of locking the automation off. A counter summed from JSON usage never
drops after a compact, so it counts from its value at the last one. The
pane parser's counter is absolute and only moves past its high, so a
move clears that baseline and it fires as it did before.

Thresholds go up to the reported window, 1M when unknown, and a higher
value stops at the window. MAX_SESSION_TOKENS follows, and the pane
parser's M-suffix guard checks that cap instead of a fixed 0.5.

Refs #585

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/utils/token-validation.ts

@@ -1,13 +1,13 @@
 /**
  * @fileoverview Token validation constants.
  *
- * Claude's context window is ~200k tokens, so 500k is a generous upper bound.
+ * Claude's context window is 200k tokens, or 1M with extended context.
  *
  * @module utils/token-validation
  */
 
 /**
  * Maximum tokens allowed per session.
- * Claude's context is ~200k, so 500k is a safe upper bound for validation.
+ * The largest context Claude reports today is 1M, the upper bound for validation.
  */
-export const MAX_SESSION_TOKENS = 500_000;
+export const MAX_SESSION_TOKENS = 1_000_000;