refactor: extract dashboard state/model layer into dashboard_model.py

Splits the 2103-line dashboard.py into two modules. Pure data
structures (QueuedProposal), discovery helpers (discover_pending,
discover_active_agents), derived-value helpers (_is_recent,
_approval_status, _format_agent_row, _detail_lines, etc.), and
argv-builder helpers (_build_split_pane_argv, _build_respawn_pane_argv,
_build_resume_argv_with_fallback, _agent_runtime_args) all move to
dashboard_model.py. The curses TUI, $EDITOR integration, tmux
subprocess flows, and action handlers (approve, reject,
operator_edit_routes, operator_edit_allowlist) remain in dashboard.py,
which re-imports everything from dashboard_model so existing callers and
tests are unaffected.

Adds tests/unit/test_dashboard_model.py covering _approval_status,
_proposed_payload_label, and _suffix_for_tool — three helpers that had
no prior coverage. All 894 unit tests pass.

Closes #158

tests/unit/test_dashboard_model.py

@@ -0,0 +1,94 @@
+"""Unit: dashboard_model — state/model layer extracted from dashboard.py.
+
+Tests for functions that were previously buried in the 2103-line
+dashboard.py and had no coverage: _approval_status,
+_proposed_payload_label, and _suffix_for_tool."""
+
+import unittest
+from pathlib import Path
+
+from bot_bottle.cli.dashboard_model import (
+    QueuedProposal,
+    _approval_status,
+    _proposed_payload_label,
+    _suffix_for_tool,
+)
+from bot_bottle.supervise import (
+    Proposal,
+    TOOL_CAPABILITY_BLOCK,
+    TOOL_EGRESS_BLOCK,
+    TOOL_PIPELOCK_BLOCK,
+    sha256_hex,
+)
+from datetime import datetime, timezone
+
+
+def _qp(tool: str, slug: str = "dev") -> QueuedProposal:
+    payload = "x"
+    p = Proposal.new(
+        bottle_slug=slug,
+        tool=tool,
+        proposed_file=payload,
+        justification="test",
+        current_file_hash=sha256_hex(payload),
+        now=datetime(2026, 6, 1, 0, 0, 0, tzinfo=timezone.utc),
+    )
+    return QueuedProposal(proposal=p, queue_dir=Path("/tmp/q"))
+
+
+class TestApprovalStatus(unittest.TestCase):
+    def test_egress_block_base_message(self):
+        qp = _qp(TOOL_EGRESS_BLOCK, slug="my-bot")
+        msg = _approval_status(qp, "approved")
+        self.assertEqual("approved egress-block for [my-bot]", msg)
+
+    def test_modified_verb(self):
+        qp = _qp(TOOL_PIPELOCK_BLOCK, slug="dev")
+        msg = _approval_status(qp, "modified+approved")
+        self.assertEqual("modified+approved pipelock-block for [dev]", msg)
+
+    def test_capability_block_appends_resume_hint(self):
+        qp = _qp(TOOL_CAPABILITY_BLOCK, slug="alpha")
+        msg = _approval_status(qp, "approved")
+        self.assertIn("resume: ./cli.py resume alpha", msg)
+        self.assertIn("approved capability-block for [alpha]", msg)
+
+    def test_egress_block_has_no_resume_hint(self):
+        qp = _qp(TOOL_EGRESS_BLOCK)
+        self.assertNotIn("resume", _approval_status(qp, "approved"))
+
+    def test_pipelock_block_has_no_resume_hint(self):
+        qp = _qp(TOOL_PIPELOCK_BLOCK)
+        self.assertNotIn("resume", _approval_status(qp, "approved"))
+
+
+class TestProposedPayloadLabel(unittest.TestCase):
+    def test_pipelock_returns_failed_url(self):
+        self.assertEqual("failed URL", _proposed_payload_label(TOOL_PIPELOCK_BLOCK))
+
+    def test_egress_returns_proposed_file(self):
+        self.assertEqual("proposed file", _proposed_payload_label(TOOL_EGRESS_BLOCK))
+
+    def test_capability_returns_proposed_file(self):
+        self.assertEqual("proposed file", _proposed_payload_label(TOOL_CAPABILITY_BLOCK))
+
+    def test_unknown_tool_returns_proposed_file(self):
+        self.assertEqual("proposed file", _proposed_payload_label("unknown-tool"))
+
+
+class TestSuffixForTool(unittest.TestCase):
+    def test_capability_block_returns_dockerfile_suffix(self):
+        self.assertEqual(".dockerfile", _suffix_for_tool(TOOL_CAPABILITY_BLOCK))
+
+    def test_egress_block_returns_txt(self):
+        self.assertEqual(".txt", _suffix_for_tool(TOOL_EGRESS_BLOCK))
+
+    def test_pipelock_block_returns_txt(self):
+        self.assertEqual(".txt", _suffix_for_tool(TOOL_PIPELOCK_BLOCK))
+
+    def test_unknown_tool_returns_txt(self):
+        self.assertEqual(".txt", _suffix_for_tool("whatever"))
+
+
+if __name__ == "__main__":
+    unittest.main()