fix(iSTA): apply clock uncertainty to output timing checks

[yipeix]

Output timing checks ignored the uncertainty of the clock associated with set_output_delay, making output setup and hold slack optimistic. Apply setup uncertainty with a negative sign and hold uncertainty with a positive sign when calculating required time. Also correct the report’s uncertainty cumulative time and output-delay increment so nonzero and negative output delays add up correctly.

With the GCD case’s 0.5 ns uncertainty, TT hold violations change from 34 to 52 and SS from 34 to 41, matching the saved PrimeTime endpoint sets. Residual cell/net delay differences remain: worst setup slack differs by 1.150 ps (TT) and 1.465 ps (SS).

Validation:

• ecc_bin builds; four focused CTests pass. The new output-uncertainty regression fails before the fix and passes afterward, including separate setup/hold values, capture-clock selection, output-delay signs, and report arithmetic. Test changes remain local as requested.
• GCD TT/SS reruns match all 52 setup and hold endpoint sets per corner; the 208-row comparison confirms unchanged data arrival times.
• example6 TT/SS reruns produce identical QoR and detailed timing JSON to the previous baseline.