fix(tmux): load tmux-continuum after oasis so auto-save works - #4

Problem

tmux-continuum auto-save (every 15 min) silently stopped working. Manual save (prefix + Ctrl-s) worked, but no automatic saves were produced.

Root cause

tmux-continuum triggers saves by injecting #(.../continuum_save.sh) into status-right. TPM loads plugins in the order they are declared in @plugin lines. The embedded guyide.conf declared tmux-continuum before tmux-oasis, so:

1. continuum injected its save hook into status-right
2. oasis then overwrote status-right with its own modules, wiping the hook

Result: the save script never ran. @continuum-save-last-timestamp stayed frozen and no new files appeared in ~/.local/share/tmux/resurrect/.

Fix

Move the @plugin tmux-plugins/tmux-continuum line (and its options) to load after the oasis theme, so continuum injects its hook into the final status-right. Added a comment explaining the ordering constraint so it is not regressed.

Verification

• go test ./internal/components/multiplexer/ passes.
• On a live install, a one-shot save.sh quiet produced a fresh resurrect file and the opencode-sessions post-save hook fired (opencode commands rewritten to :opencode --session <id>).
• After reload, tmux show-options -g status-right contains continuum_save.sh and @continuum-save-last-timestamp advances every 15 min.