ci(gitea): add gitea-doctor pre-flight to all CI jobs (F15 guard)

Wires bash scripts/gitea/doctor.sh --quiet as a pre-build step in all 4
jobs (backend, web, mobile, e2e). Catches the F15 class of failures —
stale env tokens, registry unreachable, owner-rename drift — in ~2s
instead of waiting for pnpm install to fail mid-build.

continue-on-error: true for now so warnings don't block the pipeline
during rollout. Flip to required once the doctor pattern is established
ecosystem-wide.

Pattern documented in:
  learning_ai_devops_tools/docs/docker-build-optimization-roadmap.md § E0

.gitea/workflows/ci.yml

@@ -23,6 +23,10 @@ jobs:
       - name: Pull latest
         run: git pull --ff-only origin main || true
 
+      - name: Gitea registry pre-flight (F15 guard)
+        run: bash ../learning_ai_common_plat/scripts/gitea/doctor.sh --quiet
+        continue-on-error: true
+
       - name: Install workspace dependencies
         run: HUSKY=0 pnpm install --frozen-lockfile
 
@@ -48,6 +52,10 @@ jobs:
       - name: Pull latest
         run: git pull --ff-only origin main || true
 
+      - name: Gitea registry pre-flight (F15 guard)
+        run: bash ../learning_ai_common_plat/scripts/gitea/doctor.sh --quiet
+        continue-on-error: true
+
       - name: Install workspace dependencies
         run: HUSKY=0 pnpm install --frozen-lockfile
 
@@ -73,6 +81,10 @@ jobs:
       - name: Pull latest
         run: git pull --ff-only origin main || true
 
+      - name: Gitea registry pre-flight (F15 guard)
+        run: bash ../learning_ai_common_plat/scripts/gitea/doctor.sh --quiet
+        continue-on-error: true
+
       - name: Install workspace dependencies
         run: HUSKY=0 pnpm install --frozen-lockfile
 
@@ -89,6 +101,10 @@ jobs:
       - name: Pull latest
         run: git pull --ff-only origin main || true
 
+      - name: Gitea registry pre-flight (F15 guard)
+        run: bash ../learning_ai_common_plat/scripts/gitea/doctor.sh --quiet
+        continue-on-error: true
+
       - name: Install workspace dependencies
         run: HUSKY=0 pnpm install --frozen-lockfile