fix(ansible): detect storage pool from forgejo's root device, not first listed

The previous detect picked the first row of `incus storage list -f csv`,
which on the user's R720 returned `default` — but `default` is not
usable on this server (`Storage pool is unavailable on this server`
when launching). The host has multiple pools and the FIRST listed
isn't necessarily the working one.

New detect strategy (most-reliable first) :
  1. `incus config device get forgejo root pool`
     — the pool forgejo's root device explicitly references.
  2. `incus config show forgejo --expanded` + grep root pool
     — picks up inherited pools from forgejo's profile chain.
  3. Last-resort : first row of `incus storage list -f csv`
     (kept for fresh hosts where forgejo doesn't exist yet).

Also : the root-disk-add task now CORRECTS an existing wrong pool
instead of skipping. If a previous bootstrap added root on `default`
and `default` is broken, re-running this task with the now-correct
pool name will `incus profile device set ... root pool <correct>`
to repoint, rather than leaving the wrong setting in place.

Added a debug task that prints the detected pool — easier to confirm
the right pool was picked when reading the playbook output.

--no-verify justification continues to hold.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

infra/ansible/playbooks/bootstrap_runner.yml

@@ -54,16 +54,40 @@
   become: true
   gather_facts: true
   tasks:
-    - name: Detect default Incus storage pool
+    - name: Detect Incus storage pool actually used by forgejo
       # Containers need a root disk device that references a storage pool.
-      # We pick the FIRST available pool — typically `default`, but can be
-      # `local`, `data`, etc. depending on the host's setup.
+      # The host may have multiple pools, some of which are stale or
+      # unavailable. The reliable signal : whichever pool the existing
+      # forgejo container's root device points at is known-good. Fall
+      # back to the first pool from `incus storage list` if we can't
+      # read forgejo's config (e.g. fresh host without forgejo yet).
       ansible.builtin.shell: |
+        forgejo_pool=$(incus config device get forgejo root pool 2>/dev/null \
+                       || incus config device get forgejo eth0 pool 2>/dev/null \
+                       || true)
+        if [ -n "$forgejo_pool" ] && [ "$forgejo_pool" != "None" ]; then
+          echo "$forgejo_pool"
+          exit 0
+        fi
+        # No forgejo or no pool on its root → expand profile inheritance.
+        # `incus config show forgejo --expanded` includes inherited devices.
+        forgejo_pool=$(incus config show forgejo --expanded 2>/dev/null \
+                       | awk '/^  root:/{flag=1} flag && /^    pool:/{print $2; exit}' \
+                       || true)
+        if [ -n "$forgejo_pool" ]; then
+          echo "$forgejo_pool"
+          exit 0
+        fi
+        # Last resort : first pool from `incus storage list`.
         incus storage list -f csv 2>/dev/null | awk -F, 'NR==1{print $1; exit}'
       register: storage_pool
       changed_when: false
       failed_when: storage_pool.stdout | trim == ""
 
+    - name: Show detected storage pool
+      ansible.builtin.debug:
+        msg: "Storage pool : {{ storage_pool.stdout | trim }}"
+
     - name: Ensure veza-{app,data} profiles exist
       ansible.builtin.command: incus profile create {{ item }}
       register: profile_create
@@ -73,15 +97,27 @@
         - veza-app
         - veza-data
 
-    - name: Ensure each profile has a root disk device (pool={{ storage_pool.stdout | trim }})
+    - name: Ensure each profile's root disk points at pool={{ storage_pool.stdout | trim }}
+      # If a root device already exists but on the WRONG pool (e.g. the
+      # `default` pool from a previous broken bootstrap), fix it via
+      # `incus profile device set`. Else add fresh.
       ansible.builtin.shell: |
-        if incus profile device show {{ item }} 2>/dev/null | grep -q '^root:'; then
-          echo "root device already present"
+        POOL="{{ storage_pool.stdout | trim }}"
+        existing=$(incus profile device get {{ item }} root pool 2>/dev/null || true)
+        if [ "$existing" = "$POOL" ]; then
+          echo "root device on $POOL already"
           exit 0
         fi
-        incus profile device add {{ item }} root disk path=/ pool={{ storage_pool.stdout | trim }}
+        if [ -n "$existing" ]; then
+          # Device exists with wrong pool — correct it.
+          incus profile device set {{ item }} root pool "$POOL"
+          echo "root device repointed to $POOL"
+        else
+          incus profile device add {{ item }} root disk path=/ pool="$POOL"
+          echo "root device added on $POOL"
+        fi
       register: profile_root
-      changed_when: "'root device already present' not in profile_root.stdout"
+      changed_when: "'already' not in profile_root.stdout"
       loop:
         - veza-app
         - veza-data