feat(projekt-matching): auto-tag created opportunities, add German docs (S68)

Every opportunity created by the workflow now carries the CTag
"Auto: Durch Suchagent-Treffer erstellt" (id 6a83292a186dce7b2), set via
cTagsIds directly in the create POST. The tag id is resolved at runtime
by name (EspoClient.ensure_ctag, same pattern as team_id; self-healing
after a CRM rebuild); the read-back verification now also checks the tag.
No backfill: existing opportunities and the saved "Via cowork-api
erstellt" list filter are untouched.

Live-verified end to end: synthetic trigger mail, opportunity
6a832b8f29cc86bdf created with cTagsNames containing the tag (test
artifact removed afterwards). 65/65 pytest.

Also adds the complete German technical documentation of the workflow
(docs/projekt-matching-dokumentation.md, sections 1-13 + S68 appendix).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

projekt-matching/tests/test_espocrm.py

@@ -47,6 +47,19 @@ def test_ensure_account_exact_match_and_create():
     assert payload == {"name": "Neue GmbH", "type": "Customer"}
 
 
+def test_ensure_ctag_find_and_create():
+    hits = {"list": [{"id": "t1", "name": "Auto: Durch Suchagent-Treffer erstellt"}]}
+    client = make_client([resp(body=hits)])
+    assert client.ensure_ctag("Auto: Durch Suchagent-Treffer erstellt") == "t1"
+    params = client.session.request.call_args.kwargs["params"]
+    assert params["where[0][type]"] == "equals"
+    assert params["where[0][attribute]"] == "name"
+    client = make_client([resp(body={"list": []}), resp(body={"id": "t2"})])
+    assert client.ensure_ctag("Auto: Durch Suchagent-Treffer erstellt") == "t2"
+    payload = client.session.request.call_args.kwargs["json"]
+    assert payload == {"name": "Auto: Durch Suchagent-Treffer erstellt"}
+
+
 def test_unique_opportunity_name_suffix():
     hits = {"list": [{"name": "Projekt X"}, {"name": "Projekt X (2)"}]}
     client = make_client([resp(body=hits)])