fix(mcp-config-validator): remove invented trust field (verify-first)

`.mcp.json` has no per-server `trust` key — verified 2026-06-18 against
code.claude.com/docs/en/mcp + /settings. MCP server approval is
dialog/settings-based (enableAllProjectMcpServers / enabledMcpjsonServers /
disabledMcpjsonServers), never a JSON field. The scanner's "Missing trust
level" (CA-MCP-001, medium) and "Invalid trust level" (high) were false
positives flagging a field that does not exist.

- scanner: delete both trust checks + VALID_TRUST_LEVELS; drop `trust` from
  VALID_SERVER_FIELDS so a stray `trust` is now flagged as an unknown field
- humanizer: remove the two trust-level entries
- knowledge (5 files): point to the real approval mechanism, not a trust field
- fixtures: scrub `trust` (incl. the invalid "local" in optimal-setup)
- tests: flip assertions (no trust-level finding; stray trust -> unknown
  field) + add knowledge-staleness re-freeze guards
- snapshots: reseed (marketplace-medium .mcp.json -8 tokens, hermetic)
- gap-matrix: mark the trust verify-first item DONE

Suite: 853/853 green.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Ter3E2JSi1Khgmuf2kady8

knowledge/claude-code-capabilities.md

@@ -228,7 +228,7 @@ paths: ["src/**/*.ts"]
       "type": "stdio|http",
       "command": "...", "args": [...],
       "url": "...",
-      "env": {}, "timeout": 30000, "trust": "workspace|trusted|untrusted"
+      "env": {}, "timeout": 30000
     }
   }
 }
@@ -236,7 +236,7 @@ paths: ["src/**/*.ts"]
 
 **Fully utilizing:** Team-shared MCP servers (GitHub, Jira, DBs); MCP resources via `@server:path`; MCP prompts as slash commands; `enableAllProjectMcpServers: true` for zero-friction team onboarding.
 
-**Common gaps:** No `.mcp.json`; MCP only configured in `~/.claude.json` (not shared); trust levels not set; MCP resources not used.
+**Common gaps:** No `.mcp.json`; MCP only configured in `~/.claude.json` (not shared); project servers not approved via `enableAllProjectMcpServers`/`enabledMcpjsonServers`; MCP resources not used.
 
 ---