fix(qoder): expand ${QODER_PLUGIN_ROOT} in plugin hook commands

[lingbin]

.qoder-plugin/plugin.json loads hooks/qoder-hooks.json as a live plugin
hook config, but the two commands contained the literal placeholder
PONYTAIL_DIR. Qoder never expands PONYTAIL_DIR, so it ran the string
verbatim:

node /PONYTAIL_DIR/hooks/ponytail-mode-tracker.js
Error: Cannot find module '...MODULE_NOT_FOUND'

surfacing in Qoder as a non-blocking UserPromptSubmit hook error on
every prompt, with the ponytail ruleset never injected -- a functional
silent failure despite the non-blocking status.

Qoder expands ${QODER_PLUGIN_ROOT} (the plugin install root) in plugin
hook commands at runtime [1], the same mechanism the sibling
hooks/claude-codex-hooks.json already uses via ${CLAUDE_PLUGIN_ROOT}.
Swap the placeholder for that variable in both commands and reword the
now-stale _comment: the file is loaded live by the plugin manifest, not
copied into settings.json as a template.

commandWindows / timeout / statusMessage from claude-codex-hooks.json
are intentionally not mirrored: the Qoder plugin-hook docs document only
"type" and "command" hook keys [1], so adding the rest would be
unverified speculation.

Verified: with QODER_PLUGIN_ROOT set, both hook scripts exit 0 and the
mode-tracker emits the "PONYTAIL MODE ACTIVE -- level: full" banner plus
the full ruleset (its isQoder double-duty branch), restoring ponytail
behavior under Qoder.

[1] https://docs.qoder.com/en/cli/plugins#writing-plugin-hooks