Add KV cache phase 0 baseline report

[guelfoweb]

Summary:

• Adds a phase 0 KV cache baseline report.
• Records no-MTP local measurements for chat, tools-on overhead, file-read, fetch_url, list_directory, system_info, long prompt, repeat, reset, and tools mode switching.
• Identifies tools-on static prompt overhead and unreliable same-session repeat cache reuse as phase 1 diagnostic targets.
• Does not change runtime, backend, prompts, tools, MTP, or KV cache behavior.

Validation:

• git diff --check: PASS

Scope:

• docs only
• analysis/report only
• no tag realignment