docs: migrate repository guidance to Gitea

.scratch/remove-original-decision-trace/issues/01-remove-original-decision-trace.md

@@ -1,6 +1,6 @@
 # 01 — Remove the original decision trace end to end
 
-**GitLab:** [#76](https://gitlab.nessar.fr/nessar/vac-optimizer/-/work_items/76)
+**Gitea:** [#76](https://gitea.nessar.fr/nessar/vac-optimizer/issues/76)
 
 ## What to build
 

.scratch/remove-original-decision-trace/issues/02-verify-trace-free-planning.md

@@ -1,6 +1,6 @@
 # 02 — Verify integrated planning after trace removal
 
-**GitLab:** [#77](https://gitlab.nessar.fr/nessar/vac-optimizer/-/work_items/77)
+**Gitea:** [#77](https://gitea.nessar.fr/nessar/vac-optimizer/issues/77)
 
 Blocked by: #76
 
@@ -24,4 +24,4 @@ The removal is agreed; its measured speedup is unresolved and is now evaluated i
 
 ## Blocked by
 
-- #76 — Remove the original decision trace end to end (https://gitlab.nessar.fr/nessar/vac-optimizer/-/work_items/76).
+- #76 — Remove the original decision trace end to end (https://gitea.nessar.fr/nessar/vac-optimizer/issues/76).

.scratch/remove-original-decision-trace/issues/03-verify-and-optimize-planning-benchmarks.md

@@ -1,6 +1,6 @@
 # 03 — Verify and optimize planning to meet the benchmarks from #75
 
-**GitLab:** [#78](https://gitlab.nessar.fr/nessar/vac-optimizer/-/work_items/78)
+**Gitea:** [#78](https://gitea.nessar.fr/nessar/vac-optimizer/issues/78)
 
 Blocked by: #75, #77