fix(clock): don't fire future timers during ProcessEvents

[denisraison]

Problem

ProcessEvents is supposed to drain pending async work (microtasks, fetches, posted events). It currently calls Clock.RunAll, which fast-forwards through every scheduled timer regardless of when it was due.

I hit this running an htmx app under gost-dom: htmx schedules a 60s defensive abort timer when a request starts, and ProcessEvents was firing it mid-request, cancelling fetches still in flight.

Fix

Introduce runDueTasks: drain microtasks and any timers whose scheduled time has already passed, but leave future-scheduled timers alone. They still fire when Advance reaches them, same as before.

Includes a regression test covering the htmx-style scenario (scheduled-but-not-due timer should not fire during ProcessEvents).

Notes

Small, isolated change in internal/clock. No public API change.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: ASSERTIVE

Plan: Pro

Run ID: 424f36c3-5bce-40b5-afa8-ed473926df99

📥 Commits

Reviewing files that changed from the base of the PR and between 40953c9 and d242a3f.

📒 Files selected for processing (2)

• internal/clock/clock.go
• internal/clock/clock_test.go

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Walkthrough

This PR modifies clock event simulation to prevent unrelated future-scheduled timers from executing during event processing. A new runDueTasks helper runs microtasks and only those timer tasks already due by the current simulated time, replacing the prior RunAll behavior that executed all queued timers. The method ProcessEventsWhile now uses this new helper to make forward progress on real async work without fast-forwarding through long-delay timeouts. A test verifies that future timers armed separately from events do not fire during ProcessEvents and only execute when the clock is explicitly advanced.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately summarizes the main change: preventing future timers from firing during ProcessEvents, which is the core fix addressed in this PR.
Description check	✅ Passed	The description is well-related to the changeset, clearly explaining the problem (ProcessEvents firing future timers prematurely), the solution (runDueTasks helper), and the testing approach.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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