migrate to SQLite and prepare for MCP deployment

Switch from PostgreSQL to SQLite (modernc.org/sqlite, pure Go) for
simpler deployment on the MCP platform. Fix URL normalization to
preserve query parameters so sites like YouTube deduplicate correctly.
Add Dockerfile, Makefile, and MCP service definition. Add pg2sqlite
migration tool. Support $PORT env var for MCP port assignment.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

templates/index.tpl

@@ -20,8 +20,8 @@
     {{ end }}
     <form action="/" method="POST">
 <input type="text" id="value" name="value" /><br />
-<label for="rawp">Don't normalize</label>
-<input type="checkbox" id="rawp" name="rawp">
+<label for="strip">Strip query string</label>
+<input type="checkbox" id="strip" name="strip">
 <br />
 <input type="submit" value="Submit">
     </form>