Snapshot axis keys are consistent across the snapshot-reporting MCP tools

Four MCP tools report the live snapshot’s availability and freshness, and they spell the two keys two different ways. McpWire.writeSnapshotAxes writes snapshotAvailability / snapshotFreshness and its javadoc states the reason for the prefix ("so the axes never collide with a tool’s own payload fields"); diagnostics and edges call it. status (GraphitronMcpServer.statusResult) and schema (SchemaView) hand-roll the same exhaustive switch over the LspSchemaSnapshot permits and write bare availability / freshness instead. So the shared helper documents a convention that half its potential callers do not follow, and the divergence is duplication rather than a decision: neither hand-rolled site has a stated reason for the shorter keys.

Why it matters: an agent reading structured content across tools cannot use one key to answer "is this answer current". It has to know which of two spellings a given tool uses, which is exactly the kind of per-tool fact the MCP surface otherwise works hard to make uniform, and the un-prefixed form is the one the helper’s javadoc argues against because it can collide with a payload field. The values are already uniform (Built / Unavailable, Current / Previous) and the freshness key is correctly omitted rather than null-valued on the unavailable arm in all four, so only the key names are at issue.

Both hand-rolled sites have a local reason to own their switch that a fix has to respect: status composes a distinct summary sentence per arm and also emits toolsReady, and SchemaView threads the freshness value into its built() helper. So the likely shape is to route the field writes through writeSnapshotAxes while leaving each site’s summary composition alone, rather than to collapse the switches. Changing the emitted key names is a wire-visible change to status and schema; the existing assertions on those tools in GraphitronMcpServerTest pin the current spelling and would need updating in the same commit, which is the right forcing function.