[WIP] Reporting (#19)

* Initial plan for issue

* Add database migration and report structures

Co-authored-by: v0l <1172179+v0l@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: v0l <1172179+v0l@users.noreply.github.com>

migrations/20250610135841_reports.sql

@@ -0,0 +1,28 @@
+-- Create reports table for file reporting functionality
+create table reports
+(
+    id          integer unsigned not null auto_increment primary key,
+    file_id     binary(32) not null,
+    reporter_id integer unsigned not null,
+    event_json  text not null,
+    created     timestamp default current_timestamp,
+
+    constraint fk_reports_file
+        foreign key (file_id) references uploads (id)
+            on delete cascade
+            on update restrict,
+    
+    constraint fk_reports_reporter
+        foreign key (reporter_id) references users (id)
+            on delete cascade
+            on update restrict
+);
+
+-- Unique index to prevent duplicate reports from same user for same file
+create unique index ix_reports_file_reporter on reports (file_id, reporter_id);
+
+-- Index for efficient lookups by file
+create index ix_reports_file_id on reports (file_id);
+
+-- Index for efficient lookups by reporter
+create index ix_reports_reporter_id on reports (reporter_id);