[-] fix task duration calculation logic

[0xgouda]

• Add task.MarkStart() and task.MarkDone() methods to update the task's StartedAt and Duration fields, invoking them respectively before and after each call to the execution functions.

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• The previous code computed task.Duration only after logging had occurred, so its value was still zero at the moment of logging. Consequently, clock_timestamp() - $5::interval always evaulated to clock_timestamp(), causing the last_run and finished fields to be identical.

Closes #788

[coveralls]

Coverage Report for CI Build 29252344674

Coverage increased (+0.2%) to 89.796%

Details

• Coverage increased (+0.2%) from the base build.
• Patch coverage: 16 of 16 lines across 4 files are fully covered (100%).
• No coverage regressions found.

Uncovered Changes

No uncovered changes found.

Coverage Regressions

No coverage regressions found.

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Coverage Stats

Relevant Lines:	2303
Covered Lines:	2068
Line Coverage:	89.8%
Coverage Strength:	1.02 hits per line

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💛 - Coveralls