Closes #364.

Why

SessionMeta only carried totalCostUsd and turnCount. On every resume /status showed:

• 0 context — summary.lastPromptTokens came from turns[0]?.usage, and turns is empty before the first live turn fires.
• 0% cache hit — aggregateCacheHitRatio summed turns[] only, so it was undefined / 0 immediately after resume.

The next API call still hit the cached prefix and answered correctly (the user's transcript shows 366,976 / 367,085 cache hits on turn 1), but the status panel claimed "no context" until that call landed.

What changes

src/memory/session.ts — extend SessionMeta:

cacheHitTokens?: number;
cacheMissTokens?: number;
lastPromptTokens?: number;

src/telemetry/stats.ts — seedCarryover accepts the three new fields. aggregateCacheHitRatio now seeds hit / miss from carryover before summing live turns. summary().lastPromptTokens falls back to the carryover when no live turn exists yet.

src/loop.ts — seedCarryover call on resume passes the new fields.

src/cli/ui/App.tsx — patchSessionMeta after assistant_final now writes:

cacheHitTokens: (m.cacheHitTokens ?? 0) + u.promptCacheHitTokens,
cacheMissTokens: (m.cacheMissTokens ?? 0) + u.promptCacheMissTokens,
lastPromptTokens: u.promptTokens, // only when truthy

Tests

• tests/telemetry.test.ts — 5 new cases: ratio with carryover-only, ratio with carryover + live, lastPromptTokens fallback + override, seedCarryover ignores zero/negative.
• tests/session.test.ts — new case: CacheFirstLoop resume preloads cache + lastPromptTokens through the meta → stats path.

Test plan

• npm run verify — 133 files / 2138 passed / 1 skipped (was 2132, +6 new)
• Manual: chat one turn → exit → resume → /status shows the prior context bar and a non-zero cache hit %, not the previous 0/0 state