style(org): use literal space in file: link targets

style(org): use literal space in file: link targets

396 [[file:…%20…]] link targets across 31 project pages were

rewritten to use a literal space instead of %20-encoding. Both

forms are accepted by org and browsers, but the project convention

is now literal space for file: links.

https: and mailto: links still use %20 where the URL path or query

string contains a space — that's mandatory per RFC 3986, and no such

links in the project had a literal space to fix. The 108 https: and

31 mailto: links in the project are unchanged.

AGENTS.org is updated to document the new rule: file: links use

literal space; https: and mailto: links use %20; the do-not-

normalise warning is replaced with the actual rule.