Fix topic page visibility and associations - #160

Topic links could open pages whose cards remained hidden, and locale auto-detection could redirect canonical English topic pages to localized routes that do not exist. The topic metadata also contained several missing or misleading associations discovered while reviewing the follow-up comment on #156.

Changes

• Render topic-page cards visible by default while preserving homepage filter behavior.
• Keep English-only topic pages on their canonical routes and correct their asset paths.
• Audit all 113 content files, removing misleading topics and adding directly demonstrated associations.
• Add a dedicated Random Number Generation topic so non-cryptographic RNG APIs are not classified as security features.

Verification

• Regenerated every locale successfully.
• Validated all 113 content files against the 44-topic taxonomy.
• Confirmed every generated topic page exactly matches its declared content associations.
• Verified the affected topic pages locally in the browser.