emrg: show running task elapsed duration + 5s status polling in GUI task panel

[argszero]

Implements the GUI task-panel improvements from rant 2026-08-22T07:18:35: show the running task's elapsed duration, and auto-refresh the running→queued state transition via 5s polling (host-confirmed polling approach — a few seconds of lag is acceptable, no event push).

Changes

emrg/server/scheduler.py — TaskHandler.status() now exposes "started_at": the current cycle's start epoch (self._start_time), valid only while running is true, None when idle/completed.

emrg/gui/renderer/js/dialogs.js

• Running task rows now render an elapsed-duration span "已运行 XXs" (app.taskRunningDuration i18n) that ticks up every second — reuses the existing taskCountdowns array mechanism, mirrored: startedAt fixed, now increases so the duration grows (vs. the pending countdown which shrinks toward its deadline).
• New startTaskPoll() / stopTaskPoll(): a 5s interval re-fetches loadTaskMeta() + renderTaskList() while the panel is active, so a task that finishes its cycle flips to "待运行" with its next-run countdown within ≤5s. Idempotent start; separate timer from the 1s countdown (the poll never restarts itself).

emrg/gui/renderer/js/app.js

• openTasksPanel() starts the poll after the initial render.
• Both view-leave paths (switchView to a non-tasks view, and toggle-close of the tasks panel) call stopTaskPoll() alongside the existing stopTaskCountdown() — same lifecycle, no leaks.

emrg/gui/renderer/js/i18n.js — new app.taskRunningDuration key in zh (已运行 {n}) and en (running for {n}).

Verification

• uv run pytest tests/: 1002 passed, 1 skipped (new assertions in test_evolution_handler_status_last_run_fields cover started_at = epoch while running, None while idle)
• python -c "from emrg.client.app import run_client": OK
• python -m emrg --help: OK
• GUI renderer smoke tests extended (elapsed tick + poll lifecycle) — executed by CI (test-windows job; no local node binary on this host)

CSS/JS + one additive daemon field; no protocol breaking changes.

[argszero]

✅ LGTM — cycle 1245. Verified the scheduler status() started_at semantics (epoch while running / None when idle, both asserted in tests), the dialogs.js elapsed-tick + 5s poll lifecycle (start on panel open, stop on both view-leave paths — no leak), and i18n keys in zh/en. CI test+test-windows green (run 32537257426).

[argszero]

Found a semantic bug during review: _start_time is set ONCE at handler start (scheduler.py run()), so the originally-shipped started_at reported cumulative handler uptime instead of THIS cycle's elapsed time — the second cycle onward would show a wrong (growing) duration. The rant explicitly asks for 本次运行时长 (this run's duration).

Fix (commit 207dcc6): added a dedicated per-cycle timestamp _cycle_start_time — set at tick begin (where _cycle_running = True), cleared in the finally block. status()['started_at'] now reads _cycle_start_time while running. _start_time is untouched, so template uptime semantics are preserved.

Tests updated to exercise _cycle_start_time (epoch while running / None when idle); full suite re-verified: 1002 passed, 1 skipped, import + CLI OK.

[argszero]

✅ LGTM — cycle 1245 (re-verified on head 207dcc6 after the per-cycle started_at fix). The scheduler change now reports THIS cycle's elapsed time via _cycle_start_time (set at tick begin, cleared at cycle end) — matching the rant's 本次运行时长 requirement; _start_time (handler uptime) semantics preserved for templates. Full suite 1002 passed + 1 skipped, import + CLI OK; CI test + test-windows green (run 32537919701).

[argszero]

✅ LGTM — cycle 1246. Fresh re-verify on head 207dcc6: per-cycle started_at semantics correct, elapsed tick + 5s poll lifecycle sound, i18n zh/en present, tests cover both states; CI test+test-windows green (run 32537919701).

[argszero]

✅ LGTM — cycle 1247. Fresh diff review vs master e6aa4d4: scheduler exposes per-cycle _cycle_start_time (set at tick begin, cleared at end) as started_at; dialogs.js elapsed tick + 5s poll lifecycle (start on open, stop on both leave paths); i18n zh/en present; tests cover running/idle states. CI test+test-windows green (run 32537919701).