fix(plan): add tier hydration and improve architecture review output (#10938)

## Summary

This PR fixes issue #10878 where architecture reviews were truncated because the regex pattern for parsing file output would stop at the first ``` encountered in the Markdown report.

## Changes

- Change file delimiters from ``` to >>>>>>>/<<<<<<< to avoid Markdown conflicts
- Add tier hydration before strategize phase in plan_executor.py
- Increase max_tokens to 16384 in llm_actors.py for longer outputs
- Increase context_max_tokens_hot from 16000 to 32000 in settings.py
- Fix get_hot_view → get_hot_fragments in strategy_actor.py and plan_executor.py
- Add opencode to skip directories in context_tier_hydrator.py
- Change sandbox output location to plan-output/ directory in plan.py
- Add get_context_summary stub method to acms_service.py

## Testing

Run architecture review action and verify the output report is complete with all sections.

Reviewed-on: #10938

features/main_error_paths.feature

@@ -0,0 +1,37 @@
+Feature: CLI main() error handling paths
+  As a developer
+  I want to cover the error-handling branches in cleveragents.cli.main
+  So that convert_exit_code(), subcommand import failure, and config validation are exercised
+
+  @coverage
+  Scenario: invalid --config-path that is a directory is rejected
+    When I run CLI with arguments ["--config-path", "/tmp", "version"]
+    Then the main cli exit code should be 1
+    And the main cli output contains "is not a file"
+
+  @coverage
+  Scenario: unknown command returns exit code 2
+    When I run CLI with arguments ["this_is_not_a_command"]
+    Then the main cli exit code should be 2
+    And the main cli output contains "Invalid command 'this_is_not_a_command'"
+
+  # These tests call convert_exit_code and _print_basic_help directly
+  @coverage
+  Scenario: convert_exit_code(None) returns 0
+    When the main exit-code converter is called with the value "None"
+    Then the main convert_exit_code result is "0"
+
+  @coverage
+  Scenario: convert_exit_code(int -1) returns -1 for negative codes
+    When the main exit-code converter is called with the value "-1"
+    Then the main convert_exit_code result is "-1"
+
+  @coverage
+  Scenario: convert_exit_code(string "abc") returns 1 for unparseable
+    When the main exit-code converter is called with the value "abc"
+    Then the main convert_exit_code result is "1"
+
+  @coverage
+  Scenario: _print_basic_help prints without error
+    When I call the main _print_basic_help
+    Then the main _print_basic_help completes ok