fix: cap context pressure percentage at 100% in display (#3480)

* fix: cap context pressure percentage at 100% in display

The forward-looking token estimate can overshoot the compaction threshold
(e.g. a large tool result pushes it from 70% to 109% in one step). The
progress bar was already capped via min(), but pct_int was not — causing
the user to see '109% to compaction' which is confusing.

Cap pct_int at 100 in both CLI and gateway display functions.

Reported by @JoshExile82.

* refactor: use real API token counts for compression decisions

Replace the rough chars/3 estimation with actual prompt_tokens +
completion_tokens from the API response. The estimation was needed to
predict whether tool results would push context past the threshold, but
the default 50% threshold leaves ample headroom — if tool results push
past it, the next API call reports real usage and triggers compression
then.

This removes all estimation from the compression and context pressure
paths, making both 100% data-driven from provider-reported token counts.

Also removes the dead _msg_count_before_tools variable.

agent/display.py

@@ -699,7 +699,7 @@ def format_context_pressure(
         threshold_percent: Compaction threshold as a fraction of context window.
         compression_enabled: Whether auto-compression is active.
     """
-    pct_int = int(compaction_progress * 100)
+    pct_int = min(int(compaction_progress * 100), 100)
     filled = min(int(compaction_progress * _BAR_WIDTH), _BAR_WIDTH)
     bar = _BAR_FILLED * filled + _BAR_EMPTY * (_BAR_WIDTH - filled)
 
@@ -729,7 +729,7 @@ def format_context_pressure_gateway(
     No ANSI — just Unicode and plain text suitable for Telegram/Discord/etc.
     The percentage shows progress toward the compaction threshold.
     """
-    pct_int = int(compaction_progress * 100)
+    pct_int = min(int(compaction_progress * 100), 100)
     filled = min(int(compaction_progress * _BAR_WIDTH), _BAR_WIDTH)
     bar = _BAR_FILLED * filled + _BAR_EMPTY * (_BAR_WIDTH - filled)