Add tracker description enrichment worker

Tracker descriptions were only filled on the agent-identification path,
so patterns resolved by domain, sibling, or fallback stayed without one,
and empty mapping upserts could clobber a researched description on the
shared catalog row.

Move description ownership to a dedicated, global common-pattern
enrichment worker. New catalog rows are queued on insert; the worker
researches a compliance-grade description with web search, records it on
the common pattern, and fans it out to every linked tracker pattern. The
mapping worker no longer generates descriptions and only propagates an
already-enriched one at link time.

Rename TrackerMappingConfig to TrackerAgentsConfig since the mapping and
enrichment agents now share it.

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

pkg/coredata/migrations/20260529T091300Z.sql

@@ -0,0 +1,31 @@
+-- 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.
+
+-- The common-pattern enrichment worker fills descriptions on
+-- common_tracker_patterns using an agent with web search, then fans the
+-- result out to every linked tracker pattern. enrichment_requested_at is
+-- the work queue (claimed FOR UPDATE SKIP LOCKED); enriched_at marks a
+-- row as terminally enriched so it is never re-enqueued.
+ALTER TABLE common_tracker_patterns
+    ADD COLUMN enrichment_requested_at TIMESTAMP WITH TIME ZONE,
+    ADD COLUMN enriched_at             TIMESTAMP WITH TIME ZONE;
+
+CREATE INDEX idx_common_tracker_patterns_enrichment
+    ON common_tracker_patterns (enrichment_requested_at)
+    WHERE enrichment_requested_at IS NOT NULL;
+
+-- Enqueue existing description-less rows for a first enrichment pass.
+UPDATE common_tracker_patterns
+SET enrichment_requested_at = NOW()
+WHERE description = '';