### Summary
Fixes long-standing ETA calculation errors in progress indicators that
have been present since February 2021. The current implementation
produces increasingly inaccurate estimates due to integer division
precision loss.
### Problem
3aeccadd04/triedb/pathdb/history_indexer.go (L541-L553)
The ETA calculation has two critical issues:
1. **Integer division precision loss**: `speed` is calculated as
`uint64`
2. **Off-by-one**: `speed` uses `+ 1`(2 times) to avoid division by
zero, however it makes mistake in the final calculation
This results in wildly inaccurate time estimates that don't improve as
progress continues.
### Example
Current output during state history indexing:
```
lvl=info msg="Indexing state history" processed=16858580 left=41802252 elapsed=18h22m59.848s eta=11h36m42.252s
```
**Expected calculation:**
- Speed: 16858580 ÷ 66179848ms = 0.255 blocks/ms
- ETA: 41802252 ÷ 0.255 = ~45.6 hours
**Current buggy calculation:**
- Speed: rounds to 1 block/ms
- ETA: 41802252 ÷ 1 = ~11.6 hours ❌
### Solution
- Created centralized `CalculateETA()` function in common package
- Replaced all 8 duplicate code copies across the codebase
### Testing
Verified accurate ETA calculations during archive node reindexing with
significantly improved time estimates.
0e69530c6e