feat: relicense AGPL-3.0 → MIT (v2.7.0)

Clear the 3 Unsloth-Studio-derived AGPL files and flip LICENSE + 5
package.json from AGPL-3.0-only to MIT.

- html-to-md.ts → MIT node-html-markdown (parse5 dropped)
- llama-args-validator.ts → clean-room (flag denylist = facts)
- tool-call-parser.ts → delete dead Unsloth-ported code; keep
  extractToolCallBlocks/stripToolMarkup byte-identical (no behavior change)
- LICENSE → MIT (Copyright (c) 2026 indifferentketchup); 5 package.json → MIT;
  AGPL SPDX headers removed; README License section; license-mit guard test
- roadmap License-debt batch marked shipped; openspec/changes/license-debt-mit

Decouples the relicense from the native-parsing retirement (the ported parser
was dead code). Server suite 519 passing; build + coder typecheck clean.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

apps/web/package.json

@@ -44,5 +44,5 @@
     "typescript": "^5.5.0",
     "vite": "^5.3.4"
   },
-  "license": "AGPL-3.0-only"
+  "license": "MIT"
 }