feat(attach): pass --resume on dashboard re-attach

Re-entering a running bottle from the dashboard (Enter on the
agents pane) now invokes claude with `--resume` so the session
picks up the prior conversation history rather than starting a
fresh transcript. The first-attach paths (`./cli.py start` and
the dashboard's new-agent `n` flow) leave it off — the
transcript doesn't exist yet there.

`attach_claude` gains a `resume: bool = False` kwarg;
`_attach_to_bottle` in the dashboard passes `True`.

claude_bottle/cli/dashboard.py

@@ -656,10 +656,15 @@ def _attach_to_bottle(
     slug: str,
 ) -> str:
     """Handoff: curses.endwin → attach claude → curses refresh.
-    Returns the post-attach status-line message."""
+    Re-entry into a running bottle from the dashboard always
+    passes `--resume` so claude picks up its prior conversation
+    rather than starting a fresh transcript — the first attach
+    happens via `_new_agent_flow` which sets up the transcript
+    in the first place. Returns the post-attach status-line
+    message."""
     curses.endwin()
     try:
-        exit_code = attach_claude(bottle, remote_control=False)
+        exit_code = attach_claude(bottle, remote_control=False, resume=True)
     except BaseException:
         stdscr.refresh()
         raise

claude_bottle/cli/start.py

@@ -92,15 +92,21 @@ def prepare_with_preflight(
 
 
 def attach_claude(
-    bottle: Bottle, *, remote_control: bool = False,
+    bottle: Bottle, *, remote_control: bool = False, resume: bool = False,
 ) -> int:
     """Run claude inside `bottle` as an interactive session. Blocks
     until the session ends; returns the claude process's exit code.
 
+    `resume=True` adds `--resume` so claude picks up its prior
+    conversation history rather than starting a fresh transcript —
+    the right shape for the dashboard's Enter re-attach (PRD 0020
+    chunk 3). First-attach paths (`./cli.py start`, the dashboard's
+    new-agent flow) leave it False.
+
     Used as the inner step of `./cli.py start` (one-shot) and by the
-    dashboard (PRD 0020), which calls it from inside a `curses.endwin
-    → … → stdscr.refresh()` handoff so the curses surface gets out
-    of the terminal's way while claude has it."""
+    dashboard, which calls it from inside a `curses.endwin → … →
+    stdscr.refresh()` handoff so the curses surface gets out of the
+    terminal's way while claude has it."""
     info(
         "attaching interactive claude session "
         "(Ctrl-D or 'exit' to leave; container will be removed)"
@@ -108,6 +114,8 @@ def attach_claude(
     claude_args = ["--dangerously-skip-permissions"]
     if remote_control:
         claude_args.append("--remote-control")
+    if resume:
+        claude_args.append("--resume")
     return bottle.exec_claude(claude_args, tty=True)