feat(v0.3): O2 — resume past Claude sessions

- src/http/history.ts: listSessions() reads ~/.claude/projects/*/*.jsonl
  (mtime-sorted, top 50), parseSessionMeta() extracts cwd + first user prompt
  (pure, 4 unit tests); GET /sessions
- terminal-session: opts.initialInput (typed ~700ms after the shell is ready)
- tabs.newTabForResume(cwd,id): new tab in the project dir running
  'claude --resume <id>'
- public/history.ts: 🕘 panel listing sessions (project · time · preview) with
  Resume buttons
- Verified: /sessions returns 44 real sessions; panel lists project/time/preview.
  216 tests green.

public/style.css

@@ -253,6 +253,73 @@ html, body {
   font-weight: 600;
 }
 
+/* History / resume modal (O2) */
+#historymodal {
+  position: fixed;
+  inset: 0;
+  z-index: 1200;
+  display: flex;
+  align-items: flex-start;
+  justify-content: center;
+  padding-top: 56px;
+  background: rgba(0, 0, 0, 0.6);
+}
+.hist-card {
+  background: #222;
+  border: 1px solid #3a3a3a;
+  border-radius: 10px;
+  min-width: 360px;
+  max-width: 92vw;
+  max-height: 72vh;
+  overflow-y: auto;
+  box-shadow: 0 8px 32px rgba(0, 0, 0, 0.5);
+}
+.hist-title {
+  padding: 12px 16px;
+  font-weight: 600;
+  color: #fff;
+  border-bottom: 1px solid #3a3a3a;
+}
+.hist-empty {
+  padding: 16px;
+  color: #aaa;
+}
+.hist-row {
+  display: flex;
+  align-items: center;
+  gap: 10px;
+  padding: 10px 16px;
+  border-bottom: 1px solid #2a2a2a;
+}
+.hist-main {
+  flex: 1 1 auto;
+  min-width: 0;
+}
+.hist-proj {
+  color: #fff;
+  font-size: 13px;
+}
+.hist-prev {
+  color: #aaa;
+  font-size: 12px;
+  overflow: hidden;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+}
+.hist-resume {
+  flex: none;
+  background: #2ea043;
+  color: #fff;
+  border: none;
+  border-radius: 5px;
+  padding: 6px 14px;
+  cursor: pointer;
+  font: inherit;
+}
+.hist-resume:hover {
+  background: #3fb950;
+}
+
 .tab {
   display: flex;
   align-items: center;