The `hermes prompt-size` command now uses `_get_platform_tools()` to resolve
platform-specific toolsets the same way the gateway does, and also honors
`agent.disabled_toolsets` from config. This fixes the discrepancy where
`prompt-size` reported more tools than actually available in real sessions
for a given platform.
Fixes#41445.
Adds a 'hermes prompt-size' command that reports the fixed prompt budget
for a fresh session: system prompt total, skills index, memory, user
profile, prompt tiers, and tool-schema JSON bytes. Runs offline (dummy
credentials force the direct-construction path, no network call).
Lets users see which block dominates their per-call payload — the skills
index is often the largest single block when many skills are installed
(issue #34667). Zero model-tool footprint: it's a top-level CLI
subcommand, not an agent tool.
--platform <name> simulates a channel's platform hint; --json emits a
machine-readable breakdown.
Closes#34667
