Add terminal E2E keystroke budgets

tools/TERMINAL_E2E.md

@@ -26,14 +26,17 @@ Artifact roles:
 - `screenshot.svg` and `terminal.html`: browser-viewable visual evidence. SVG
   includes color swatches for seen cursor/current-line/status/selection roles.
 - `widths.tsv`: per-line semantic width report used to catch viewport overflow.
+- `keystrokes.tsv`: logical user key-event count and raw byte count for scenario
+  payloads. A CSI sequence such as PageDown counts as one attached-key event
+  while still recording all raw bytes sent.
 - `raw.bin`: exact PTY bytes for low-level debugging.
 
 Golden policy:
 
 - Investigate before updating any expected artifact or assertion.
 - Prefer semantic artifacts (`manifest.tsv`, `visible-controls.normalized.txt`,
-  `transcript.txt`, `widths.tsv`) for assertions; visual artifacts explain what a
-  user would see.
+  `transcript.txt`, `widths.tsv`, `keystrokes.tsv`) for assertions; visual
+  artifacts explain what a user would see.
 - Updating artifacts is safe only after the change is intentional and the receipt
   names the changed UI/control-byte behavior.
 - Adding a mobile scenario must preserve the `ios-default-qwertz-space-path`
@@ -41,5 +44,8 @@ Golden policy:
 - Bare LF in raw-mode terminal output is a regression unless a scenario explicitly
   proves a non-raw stream. Raw-mode rendering should use CRLF to avoid diagonal
   terminal skew.
+- Scenario `max_key_events` budgets are regression guards for workflow burden,
+  not speed benchmarks. Raise a budget only after explaining the intentional
+  workflow change in the receipt.
 - Generated artifacts must remain under ignored build output and must not dirty a
   clean source tree.