refactor: extract shared helpers to deduplicate repeated code patterns (#7917)

* refactor: add shared helper modules for code deduplication

New modules:
- gateway/platforms/helpers.py: MessageDeduplicator, TextBatchAggregator,
  strip_markdown, ThreadParticipationTracker, redact_phone
- hermes_cli/cli_output.py: print_info/success/warning/error, prompt helpers
- tools/path_security.py: validate_within_dir, has_traversal_component
- utils.py additions: safe_json_loads, read_json_file, read_jsonl,
  append_jsonl, env_str/lower/int/bool helpers
- hermes_constants.py additions: get_config_path, get_skills_dir,
  get_logs_dir, get_env_path

* refactor: migrate gateway adapters to shared helpers

- MessageDeduplicator: discord, slack, dingtalk, wecom, weixin, mattermost
- strip_markdown: bluebubbles, feishu, sms
- redact_phone: sms, signal
- ThreadParticipationTracker: discord, matrix
- _acquire/_release_platform_lock: telegram, discord, slack, whatsapp,
  signal, weixin

Net -316 lines across 19 files.

* refactor: migrate CLI modules to shared helpers

- tools_config.py: use cli_output print/prompt + curses_radiolist (-117 lines)
- setup.py: use cli_output print helpers + curses_radiolist (-101 lines)
- mcp_config.py: use cli_output prompt (-15 lines)
- memory_setup.py: use curses_radiolist (-86 lines)

Net -263 lines across 5 files.

* refactor: migrate to shared utility helpers

- safe_json_loads: agent/display.py (4 sites)
- get_config_path: skill_utils.py, hermes_logging.py, hermes_time.py
- get_skills_dir: skill_utils.py, prompt_builder.py
- Token estimation dedup: skills_tool.py imports from model_metadata
- Path security: skills_tool, cronjob_tools, skill_manager_tool, credential_files
- Non-atomic YAML writes: doctor.py, config.py now use atomic_yaml_write
- Platform dict: new platforms.py, skills_config + tools_config derive from it
- Anthropic key: new get_anthropic_key() in auth.py, used by doctor/status/config/main

* test: update tests for shared helper migrations

- test_dingtalk: use _dedup.is_duplicate() instead of _is_duplicate()
- test_mattermost: use _dedup instead of _seen_posts/_prune_seen
- test_signal: import redact_phone from helpers instead of signal
- test_discord_connect: _platform_lock_identity instead of _token_lock_identity
- test_telegram_conflict: updated lock error message format
- test_skill_manager_tool: 'escapes' instead of 'boundary' in error msgs

tools/path_security.py

@@ -0,0 +1,43 @@
+"""Shared path validation helpers for tool implementations.
+
+Extracts the ``resolve() + relative_to()`` and ``..`` traversal check
+patterns previously duplicated across skill_manager_tool, skills_tool,
+skills_hub, cronjob_tools, and credential_files.
+"""
+
+import logging
+from pathlib import Path
+from typing import Optional
+
+logger = logging.getLogger(__name__)
+
+
+def validate_within_dir(path: Path, root: Path) -> Optional[str]:
+    """Ensure *path* resolves to a location within *root*.
+
+    Returns an error message string if validation fails, or ``None`` if the
+    path is safe.  Uses ``Path.resolve()`` to follow symlinks and normalize
+    ``..`` components.
+
+    Usage::
+
+        error = validate_within_dir(user_path, allowed_root)
+        if error:
+            return json.dumps({"error": error})
+    """
+    try:
+        resolved = path.resolve()
+        root_resolved = root.resolve()
+        resolved.relative_to(root_resolved)
+    except (ValueError, OSError) as exc:
+        return f"Path escapes allowed directory: {exc}"
+    return None
+
+
+def has_traversal_component(path_str: str) -> bool:
+    """Return True if *path_str* contains ``..`` traversal components.
+
+    Quick check for obvious traversal attempts before doing full resolution.
+    """
+    parts = Path(path_str).parts
+    return ".." in parts