loadSession silently drops sessions on any parse error or version mismatch (data loss masquerading as 'no session')

Opus finding

loadSession silently drops sessions on any parse error or version mismatch (data loss masquerading as 'no session')

• src/session.ts:56-75

loadSession returns null on JSON.parse failure, shape mismatch, or version skew — and the next saveSession will overwrite that file. A user who upgrades, finds their resume gone, then runs a new session loses all prior history with no warning, no backup, and no log. The comment 'silently ignore incompatible sessions' acknowledges this explicitly. For a 'power tool' that persists conversation state, silent data loss is a poor default.