Add slug-based dedup and auto-create third parties from OCD

Add a slug column to common_third_parties for stable cross-source
deduplication. The OCD tracker patterns importer now resolves third
parties via a three-step cascade (slug lookup, domain fallback,
auto-create) instead of silently dropping unmatched links.

Signed-off-by: Émile Ré <emile@probo.com>

pkg/coredata/migrations/20260514T123727Z.sql

@@ -0,0 +1,32 @@
+-- Copyright (c) 2026 Probo Inc <hello@getprobo.com>.
+--
+-- Permission to use, copy, modify, and/or distribute this software for any
+-- purpose with or without fee is hereby granted, provided that the above
+-- copyright notice and this permission notice appear in all copies.
+--
+-- THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+-- REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+-- AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+-- INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+-- LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
+-- OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+-- PERFORMANCE OF THIS SOFTWARE.
+
+ALTER TABLE common_third_parties ADD COLUMN slug TEXT;
+
+UPDATE common_third_parties
+SET slug = lower(
+    trim(BOTH '-' FROM
+        regexp_replace(
+            regexp_replace(
+                regexp_replace(name, '[^a-zA-Z0-9 _-]', '', 'g'),
+            '[ _]+', '-', 'g'),
+        '-+', '-', 'g')
+    )
+);
+
+ALTER TABLE common_third_parties ALTER COLUMN slug SET NOT NULL;
+
+DROP INDEX common_third_parties_name_key;
+
+CREATE UNIQUE INDEX common_third_parties_slug_key ON common_third_parties (slug);