Clarify repository search pagination limits

[kitsuyui]

Summary

• Name the GitHub repository search per-page size separately from the local page-count guard.
• Rename the loop counter so the guard is clearly counted in pages.
• Preserve the existing pagination guard behavior while replacing anonymous 100 literals with named units.

Verification

• cargo fmt --all -- --check
• cargo check
• cargo test
• cargo clippy -- -D warnings
• cargo build
• git diff --check
• collateral check: clean
• implement-validator: overall pass

[github-actions]

Code Metrics Report

	main (c2444fa)	#853 (8176f05)	+/-
Coverage	74.3%	74.3%	0.0%
Code to Test Ratio	1:0.0	1:0.0	-0.1
Test Execution Time	42s	5m21s	+4m39s

Details

  |                     | main (c2444fa) | #853 (8176f05) |  +/-   |
  |---------------------|----------------|----------------|--------|
  | Coverage            |          74.3% |          74.3% |   0.0% |
  |   Files             |             18 |             18 |      0 |
  |   Lines             |           2010 |           2010 |      0 |
  |   Covered           |           1495 |           1495 |      0 |
- | Code to Test Ratio  |          1:0.0 |          1:0.0 |   -0.1 |
  |   Code              |           2606 |           2608 |     +2 |
  |   Test              |             20 |             20 |      0 |
- | Test Execution Time |            42s |          5m21s | +4m39s |

Code coverage of files in pull request scope (0.0% → 0.0%)

Files	Coverage	+/-	Status
src/github/api.rs	0.0%	0.0%	modified

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Reported by octocov