fix: differentiate ToC indentation for each heading level

[k1LoW]

Summary

• Fix ToC panel so each heading level (h1–h6) has distinct indentation instead of h1 and h2 sharing the same level

[github-actions]

Code Metrics Report

	main (96fbfbf)	#30 (cda1da5)	+/-
Coverage	10.5%	10.5%	0.0%
Code to Test Ratio	1:0.1	1:0.1	0.0
Test Execution Time	21s	21s	0s

Details

  |                     | main (96fbfbf) | #30 (cda1da5) | +/-  |
  |---------------------|----------------|---------------|------|
  | Coverage            |          10.5% |         10.5% | 0.0% |
  |   Files             |              5 |             5 |    0 |
  |   Lines             |            494 |           494 |    0 |
  |   Covered           |             52 |            52 |    0 |
  | Code to Test Ratio  |          1:0.1 |         1:0.1 |  0.0 |
  |   Code              |           1546 |          1546 |    0 |
  |   Test              |            161 |           161 |    0 |
  | Test Execution Time |            21s |           21s |   0s |

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Reported by octocov