P12-T1: Add MCP Client Identification

[SoundBlaster]

Description

Detects the MCP client identity from the initialize handshake and surfaces it in the dashboard. The clientInfo field (name, version) is extracted from the initialize request params, stored in both in-memory metrics and the SQLite shared store, and displayed in a new "Active Client" KPI card on the dashboard.

Changes:

• schemas.py: Added MCPClientInfo, MCPInitializeParams models; added clientInfo field to MCPParams; added MCPRequest.get_client_info() method
• __main__.py: In on_request(), capture clientInfo from initialize method; call metrics.set_client_info() (defaults to "unknown" if absent)
• webui/metrics.py: Added set_client_info(), client_name/client_version in get_summary(), reset clears to "unknown"
• webui/shared_metrics.py: Added client_info table (single-row upsert), set_client_info(), client fields in get_summary(), reset() clears client info
• webui/static/index.html: Added "Active Client" KPI card (kpi-client)
• webui/static/dashboard.js: updateKPIs() renders client_name + " " + client_version

Type of Change

• Bug fix
• New feature
• Documentation update
• Refactoring
• CI/CD improvement

Quality Gates

• make test - All tests pass with ≥90% coverage (413 passed, 5 skipped; 96.04% coverage)
• make lint - No linting errors (ruff check src/ clean)
• make format - Code is properly formatted
• make typecheck - Type checking passes (mypy src/ clean, 13 files)
• make doccheck - Documentation is synced with DocC (if docs changed)

Documentation Sync

• Documentation changes are synced with DocC catalog (or N/A) — no docs/ files changed

Testing

• Added/updated tests for new functionality — 10 new tests across test_main.py, test_metrics.py, test_shared_metrics.py
• All tests pass locally
• Manually tested the changes

New tests cover:

• test_main_captures_client_info_from_initialize — clientInfo extracted and forwarded to metrics
• test_main_defaults_unknown_when_no_client_info — missing clientInfo defaults to "unknown"
• TestMetricsCollectorClientInfo (4 tests) — set/overwrite/reset behavior in MetricsCollector
• TestSharedMetricsStoreClientInfo (4 tests) — set/upsert/reset in SQLite SharedMetricsStore

Validation report: SPECS/ARCHIVE/P12-T1_Add_MCP_Client_Identification/P12-T1_Validation_Report.md

Checklist

• Code follows the project's style guidelines
• Self-review completed
• Comments added for complex code
• Documentation updated (if needed)
• No new warnings generated
• PR title is descriptive