Add log analytics and observability skill references

[arjunkumargiri]

Summary

Adds log analytics and observability capabilities to the opensearch-launchpad skill, based on the requirements from opensearch-project/observability-stack#119 and the sample implementation in opensearch-project/observability-stack#120.

What's included

Updated SKILL.md:

• Extended description with log analytics and observability trigger keywords (778 chars, within 1024 spec limit)
• Added observability routing table pointing to 3 focused reference files
• Added connection defaults, index patterns, and base PPL command for observability
• Fixed MCP auto-install messaging to ask user to restart IDE

New reference files under references/observability/:

File	Lines	Description
log-analytics.md	~360	Discovery-first log analytics workflow: discover indices, understand schema, ask clarifying questions, perform analytics with PPL. Supports any log schema (ECS, OTel, syslog, custom JSON). Instructs agent to use opensearch-mcp-server-py for AOS/AOSS with full auto-install flow.
traces.md	~207	OTel trace investigation: agent invocations, tool executions, slow spans, error spans, token usage, service maps, trace tree reconstruction.
ppl-reference.md	~230	PPL language reference: 50+ commands, 14 function categories, observability examples. Instructs agent to search OpenSearch docs when syntax is unclear.

Design decisions

• Merged into launchpad skill (not a separate skill) so users get observability capabilities without a separate install
• Discovery-first approach for log analytics: agent discovers indices, inspects mappings, samples documents, and asks clarifying questions before writing queries
• opensearch-mcp-server-py as preferred connection method for AOS/AOSS (handles SigV4 transparently), with curl as fallback for local clusters
• Deferred metrics/SLO/correlation: focused on logs and traces for the initial release
• Follows Agent Skills spec: SKILL.md under 500 lines, description under 1024 chars, reference files loaded on demand

Testing

• All 215 agent skills tests pass
• SKILL.md: 214 lines (spec recommends under 500)
• Description: 778 chars (spec max 1024)