ci: remove /ci-all — Pi cannot sustain parallel Docker containers

The Pi runner (3-4 GB RAM, swap heavily loaded) OOMs when /ci-all
triggers test-cgal + quality-gates + doc-build + links simultaneously:
four Docker containers start at once after test-fast completes, each
consuming 150-400 MB, exhausting available RAM.

Fix: /ci-all removed from all three workflow files.  Each keyword
now triggers exactly one job — no parallel container competition.

Safe workflow: one keyword per commit.
  Typical sequence:
    git commit -m 'fix: ... /test-cgal'   → CGAL tests (~5 min)
    git commit -m 'chore: /quality-gates' → style checks (~30 s)

CLAUDE.md: CI table updated with Pi-runner warning note.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.gitea/workflows/cpp-tests.yml

@@ -3,11 +3,13 @@ name: C++ Tests
 # Trigger keywords in commit message (checked via head_commit.message):
 #   /test-cgal      — full CGAL test suite (277 tests, ~5 min build)
 #   /quality-gates  — license, codespell, shellcheck, CGAL conventions
-#   /ci-all         — all of the above + /docs + /links (across all workflows)
+#
+# ⚠  /ci-all was removed: the Pi runner (3-4 GB RAM) cannot sustain
+#    multiple Docker containers simultaneously.  Use one keyword per commit.
 #
 # Examples:
 #   git commit -m "fix: correct angle formula /test-cgal"
-#   git commit -m "release prep /ci-all"
+#   git commit -m "chore: update headers /quality-gates"
 #
 # test-fast always runs on every push — it is fast (< 5 s) and cheap.
 
@@ -76,9 +78,7 @@ jobs:
 # ─────────────────────────────────────────────────────────────────────────────
   test-cgal:
     needs: test-fast
-    if: |
-      contains(github.event.head_commit.message, '/test-cgal') ||
-      contains(github.event.head_commit.message, '/ci-all')
+    if: contains(github.event.head_commit.message, '/test-cgal')
     runs-on: eulernest
     container:
       image: git.eulernest.eu/conformallab/ci-cpp:latest
@@ -133,9 +133,7 @@ jobs:
 # Cheap (~30 s): license headers, CGAL conventions, codespell, shellcheck.
 # ─────────────────────────────────────────────────────────────────────────────
   quality-gates:
-    if: |
-      contains(github.event.head_commit.message, '/quality-gates') ||
-      contains(github.event.head_commit.message, '/ci-all')
+    if: contains(github.event.head_commit.message, '/quality-gates')
     runs-on: eulernest
     container:
       image: git.eulernest.eu/conformallab/ci-cpp:latest

.gitea/workflows/doc-build.yaml

@@ -27,8 +27,7 @@ jobs:
   doc-build:
     if: |
       github.event_name == 'workflow_dispatch' ||
-      contains(github.event.head_commit.message, '/docs') ||
-      contains(github.event.head_commit.message, '/ci-all')
+      contains(github.event.head_commit.message, '/docs')
     runs-on: eulernest
     container:
       image: git.eulernest.eu/conformallab/ci-cpp:latest

.gitea/workflows/markdown-links.yml

@@ -27,8 +27,7 @@ jobs:
     if: |
       github.event_name == 'schedule' ||
       github.event_name == 'workflow_dispatch' ||
-      contains(github.event.head_commit.message, '/links') ||
-      contains(github.event.head_commit.message, '/ci-all')
+      contains(github.event.head_commit.message, '/links')
     runs-on: eulernest
     container:
       image: git.eulernest.eu/conformallab/ci-cpp:latest