test: strengthen assertions across 7 test files (batch 1)

Replaced weak 'is not None' / '> 0' / 'len >= 1' assertions with
concrete value checks across the most flagged test files:

gateway/test_pairing.py (11 weak → 0):
  - Code assertions verify isinstance + len == CODE_LENGTH
  - Approval results verify dict structure + specific user_id/user_name
  - Added code2 != code1 check in rate_limit_expires

test_hermes_state.py (6 weak → 0):
  - ended_at verified as float timestamp
  - Search result counts exact (== 2, not >= 1)
  - Context verified as non-empty list
  - Export verified as dict, session ID verified

test_cli_init.py (4 weak → 0):
  - max_turns asserts exact value (60)
  - model asserts string with provider/name format

gateway/test_hooks.py (2 zero-assert tests → fixed):
  - test_no_handlers_for_event: verifies no handler registered
  - test_handler_error_does_not_propagate: verifies handler count + return

gateway/test_platform_base.py (9 weak image tests → fixed):
  - extract_images tests now verify actual URL and alt_text
  - truncate_message verifies content preservation after splitting

cron/test_scheduler.py (1 weak → 0):
  - resolve_origin verifies dict equality, not just existence

cron/test_jobs.py (2 weak → 0 + 4 new tests):
  - Schedule parsing verifies ISO timestamp type
  - Cron expression verifies result is valid datetime string
  - NEW: 4 tests for update_job() (was completely untested)

tests/test_cli_init.py

@@ -23,7 +23,7 @@ class TestMaxTurnsResolution:
     def test_default_max_turns_is_integer(self):
         cli = _make_cli()
         assert isinstance(cli.max_turns, int)
-        assert cli.max_turns > 0
+        assert cli.max_turns == 60
 
     def test_explicit_max_turns_honored(self):
         cli = _make_cli(max_turns=25)
@@ -32,7 +32,7 @@ class TestMaxTurnsResolution:
     def test_none_max_turns_gets_default(self):
         cli = _make_cli(max_turns=None)
         assert isinstance(cli.max_turns, int)
-        assert cli.max_turns > 0
+        assert cli.max_turns == 60
 
     def test_env_var_max_turns(self, monkeypatch):
         """Env var is used when config file doesn't set max_turns."""
@@ -54,7 +54,7 @@ class TestMaxTurnsResolution:
     def test_max_turns_never_none_for_agent(self):
         """The value passed to AIAgent must never be None (causes TypeError in run_conversation)."""
         cli = _make_cli()
-        assert cli.max_turns is not None
+        assert isinstance(cli.max_turns, int) and cli.max_turns == 60
 
 
 class TestVerboseAndToolProgress:
@@ -81,4 +81,4 @@ class TestProviderResolution:
     def test_model_is_string(self):
         cli = _make_cli()
         assert isinstance(cli.model, str)
-        assert len(cli.model) > 0
+        assert isinstance(cli.model, str) and '/' in cli.model