fix: 2 bugs fixed, 17 tests added for hook scripts

Bug fixes:
- evaluate-session.js: whitespace-tolerant regex for counting user
  messages in JSONL transcripts (/"type":"user"/ → /"type"\s*:\s*"user"/)
- session-end.js: guard against null elements in content arrays
  (c.text → (c && c.text) to prevent TypeError)

New tests (17):
- evaluate-session: whitespace JSON regression test
- session-end: null content array elements regression test
- post-edit-console-warn: 5 tests (warn, skip non-JS, clean files,
  missing file, stdout passthrough)
- post-edit-format: 3 tests (empty stdin, non-JS skip, invalid JSON)
- post-edit-typecheck: 4 tests (empty stdin, non-TS skip, missing file,
  no tsconfig)

Total test count: 191 (up from 164)

scripts/hooks/evaluate-session.js

@@ -81,8 +81,8 @@ async function main() {
     process.exit(0);
   }
 
-  // Count user messages in session
-  const messageCount = countInFile(transcriptPath, /"type":"user"/g);
+  // Count user messages in session (allow optional whitespace around colon)
+  const messageCount = countInFile(transcriptPath, /"type"\s*:\s*"user"/g);
 
   // Skip short sessions
   if (messageCount < minSessionLength) {