Fix empty Spark graph opening shift for v0.3.2

[ClaudiuSchuster]

What changed

• Give nested Spark activity charts their final horizontal insets before their
  first hidden layout frame, so a manually opened empty chart cannot move left
  when Cinnamon finishes the disclosure animation.
• Route initial and later chart-inset synchronization through the same helper
  and add a source-level lifecycle regression.
• Prepare the focused fix as patch release 0.3.2.

Security and privacy impact

None. Codex authentication, subprocess execution, analytics/history data,
local settings and screenshots are unchanged. The change only affects popup
layout styling and contains no account-specific values, credentials, private
paths or new captured media.

Verification

• make check (via make verify on commit
  5a6384561830b8989ed60ca17cb9903b1fe5b415)
• Behavior-specific regression coverage verifies that initial and
  synchronized nested-chart insets use one layout path.
• No panel actor changed. The orientation-independent popup path was
  validated on the live right/vertical placement.
• Optional Spark 5h behavior was tested in both zero-activity/manual-open
  and positive-activity/automatic-open states.
• No credentials, tokens, private paths or account-specific details appear
  in code, fixtures, logs or screenshots.
• Version metadata and the changelog are updated for 0.3.2; the documented
  feature set and screenshots remain current.
• Super-Linter 8.7.0 passed locally from the workflow-pinned image.
• Live geometry stayed at x=1499 with 5/55 px insets across all 35 sampled
  opening frames; before the fix it moved from x=1504 to x=1499.
• The installed applet audit reported 10/10 regular files, no symlinks and
  no mismatches; the live 0.3.2 instance had a healthy snapshot and no
  error.