Fix Bp Docs

When a duplicate is found, keep the version in the more appropriate category file and remove the other. Preserve all anchor IDs on the kept version so existing links don't break.

Do NOT create reference-only stubs that just point to another rule. Either keep the full rule or remove it entirely.

Step 4: Check for Stale Brave File References

Extract all brave/... file paths from code examples and verify they exist in src/brave/. For each missing file:

1. Search for the renamed/moved file using find or Glob
2. Update the reference to the correct current path
3. If the file was deleted entirely and no replacement exists, update the example to use a file that does exist

Skip paths that are obviously placeholder/illustrative (e.g., brave/components/my_feature/my_header.h, brave/chromium_src/path/to/override.h).

Step 5: Check for Stale Chromium File References

Extract Chromium file paths (e.g., components/omnibox/browser/..., chrome/browser/ui/...) from code examples and verify they exist in src/. For each missing file:

1. Search for the renamed/moved file
2. Update the reference

Skip paths that are obviously placeholder/illustrative.

Step 6: Check for Stale Chromium Symbols

Look for references to specific Chromium class names, method names, and other symbols in code examples. Verify they still exist in the Chromium source (src/). Update any that were renamed.

Step 7: Check for Stale Brave Symbols

Look for references to specific Brave class names, method names, and other symbols in code examples. Verify they still exist in src/brave/. Update any that were renamed or removed.

Step 8: Check for Broken Internal References

Look for:

• Links to other docs or files that don't exist (e.g., ../testing-requirements.md)
• References to anchor IDs that don't exist in the target file
• Links to external URLs that are clearly wrong (but don't fetch them)

Step 9: Check for Formatting Issues

Look for:

• Missing --- separators between rules
• Missing anchor IDs (<a id="...">)
• Duplicate --- separators
• Inconsistent heading levels

Step 10: Check the Index

Verify docs/best_practices.md:

• All listed docs exist
• No doc is listed twice
• All docs in $DOCS_DIR/ are represented in the index

Step 11: Report and Fix

For each issue found:

1. Describe the issue clearly
2. Fix it directly using Edit
3. Move on to the next issue

After all fixes, run ID validation:

python3 ./script/manage-bp-ids.py --validate

Important Guidelines

• No Claude Code attribution in commits or PRs
• Never remove anchor IDs even when removing duplicate rules — move them to the kept version
• Never create reference-only stubs that just point to another rule
• Preserve the style of each document when making edits
• Keep examples realistic — when updating a stale file path, pick a real file that makes sense in context
• When a code example uses a placeholder path (like path/to/foo.h), leave it alone