feat(cron): honor hermes tools config for the cron platform (#14798)

Cron now resolves its toolset from the same per-platform config the
gateway uses — `_get_platform_tools(cfg, 'cron')` — instead of blindly
loading every default toolset.  Existing cron jobs without a per-job
override automatically lose `moa`, `homeassistant`, and `rl` (the
`_DEFAULT_OFF_TOOLSETS` set), which stops the "surprise $4.63
mixture_of_agents run" class of bug (Norbert, Discord).

Precedence inside `run_job`:
  1. per-job `enabled_toolsets` (PR #14767 / #6130) — wins if set
  2. `_get_platform_tools(cfg, 'cron')` — new, the blanket gate
  3. `None` fallback (legacy) — only on resolver exception

Changes:
- hermes_cli/platforms.py: register 'cron' with default_toolset
  'hermes-cron'
- toolsets.py: add 'hermes-cron' toolset (mirrors 'hermes-cli';
  `_get_platform_tools` then filters via `_DEFAULT_OFF_TOOLSETS`)
- cron/scheduler.py: add `_resolve_cron_enabled_toolsets(job, cfg)`,
  call it at the `AIAgent(...)` kwargs site
- tests/cron/test_scheduler.py: replace the 'None when not set' test
  (outdated contract) with an invariant ('moa not in default cron
  toolset') + new per-job-wins precedence test
- tests/hermes_cli/test_tools_config.py: mark 'cron' as non-messaging
  in the gateway-toolset-coverage test

toolsets.py

@@ -295,7 +295,18 @@ TOOLSETS = {
         "tools": _HERMES_CORE_TOOLS,
         "includes": []
     },
-    
+
+    "hermes-cron": {
+        # Mirrors hermes-cli so cron's "default" toolset is the same set of
+        # core tools users see interactively — then `hermes tools` filters
+        # them down per the platform config. _DEFAULT_OFF_TOOLSETS (moa,
+        # homeassistant, rl) are excluded by _get_platform_tools() unless
+        # the user explicitly enables them.
+        "description": "Default cron toolset - same core tools as hermes-cli; gated by `hermes tools`",
+        "tools": _HERMES_CORE_TOOLS,
+        "includes": []
+    },
+
     "hermes-telegram": {
         "description": "Telegram bot toolset - full access for personal use (terminal has safety checks)",
         "tools": _HERMES_CORE_TOOLS,