Data plugin should not force history and trend charts for latest-value KPI requests

Bug description

The official curated data-analytics plugin requires fetching history and showing a trend for every metric/KPI answer, even when the user explicitly asks only for the latest value or a period-over-period change.

Current source

• Plugin: data-analytics 1.0.8
• Remote plugin ID: Plugin_fc9843a6fb34819195d6c7802398a8a7
• File: skills/index/SKILL.md, lines 73-79

The current rule says:

For a metric or KPI, fetch available history and show a trend, even when the user asks only for the latest value or a period-over-period change.

The focused visualize-data Skill in the same plugin already supports KPI cards or compact tables for latest values and recommends trend charts for movement/relationship questions.

Steps to reproduce

1. Ask Data for one current KPI value, for example: "What is today's active-user count? Return only the latest value."
2. Follow the index Skill's inline-answer rules.
3. The Skill requires an additional historical query and trend visualization despite the explicit latest-value scope.

Actual behavior

• unnecessary historical data retrieval;
• extra query cost and latency;
• an unrequested visualization;
• conflict with the focused visualization guidance.

Expected behavior

Answer a latest-value request with the latest value and its necessary source/as-of context. Fetch history and render a trend only when requested or when the analytical question actually depends on movement over time.

Proposed minimal change

Replace the unconditional history/trend rule with a conditional one, for example:

Fetch history and show a trend when the user asks about movement, trend, anomaly, or historical context; do not expand a latest-value-only request unless history is required to establish correctness.

Start with skills/index/SKILL.md lines 73-79 in the data-analytics plugin and compare its KPI guidance with the focused visualize-data Skill. Update the unconditional history/trend instruction so latest-value requests return the value with source/as-of context, while trend visualizations remain for movement, anomaly, or historical questions.