feat(config-audit): TOK consumes readActiveConfig (v5 F1)

Removes the v4 'void readActiveConfig' placeholder and wires the
active-config snapshot into the TOK scanner.

Per-turn behavior changes:
- Each enabled MCP server becomes its own hotspot entry (richer than
  the parent .mcp.json file alone)
- total_estimated_tokens now includes MCP server cost
- result.activeConfig exposes a small summary
  (claudeMdEstimatedTokens, mcpServerCount, pluginCount, skillCount)

Failures of readActiveConfig are non-fatal — the scanner falls back
to the discovery-only path used in v4.

Tests: +3 cases on the new tok-active-config fixture
(.mcp.json with 2 servers, CLAUDE.md, plugin skeleton).

plugins/config-audit/tests/fixtures/tok-active-config/CLAUDE.md

@@ -0,0 +1,14 @@
+# Tok Active-Config Fixture
+
+A small Claude Code-shaped project used by the TOK scanner integration test.
+
+## Purpose
+
+Verify that the TOK scanner consumes `readActiveConfig` output: MCP servers
+appear in hotspots and the CLAUDE.md cascade contributes a non-zero token
+estimate when active-config integration is wired up (v5 F1).
+
+## Notes
+
+This file is intentionally larger than a one-liner so the cascade contributes
+visible tokens to `activeConfig.claudeMd.estimatedTokens`.