feat: Replace unprintable characters with control pictures

[adamspofford]

Replaces unprintable ASCII characters with their equivalents from the Unicode 'Control Pictures' block.

[zeropath-ai]

✅ No security or compliance issues detected. Reviewed everything up to b37a08c.

Security Overview

• 🔎 Scanned files: 13 changed file(s)
• 🔗 Scan Link: https://zeropath.com/app/repositories/ad75df36-1e5d-46c8-bb94-503b66f5bca2?scanId=367ab964-603c-4cf9-93f5-abd162b66dcd&codeScanTypes=PrScan&tab=issues&detectionTypes=traditional,businessLogic,customRule,IAC,SECRETS,CICD,EOL,uncategorized

Detected Code Changes

Change Type	Relevant files
Enhancement	► src/lib/format/mod.rs     Introduce TerminalSafe escaper and escape function; add depicted control-picture logic
Enhancement	► src/lib/format/templates/ckbtc/retrieve_btc_err.txt     Use indentf(4) for error message formatting
Enhancement	► src/lib/format/templates/ckbtc/update_balance_err.txt     Use indentf(4) for error message formatting
Enhancement	► src/lib/format/templates/ledger/icrc1_transfer_err.txt     Use indentf(4) for error message formatting
Enhancement	► src/lib/format/templates/nns/full_neuron_info.txt     Apply flat filter and indentf(4) to certain fields
Enhancement	► src/lib/format/templates/nns/manage_neuron.txt     Apply indentf(4) to error messages
Enhancement	► src/lib/format/templates/nns/min_neuron_info.txt     Apply flat and indentf(4) to fields
Enhancement	► src/lib/format/templates/nns/proposal_info.txt     Apply flat and indentf(4) to title/summary/url and other fields; indent proposal action/description/metadata
Enhancement	► src/lib/format/templates/sns/manage_neuron.txt     Apply indentf(4) to error message
Enhancement	► src/lib/format/tests.rs     Add extensive tests for control code depiction, flat/indent behavior, and per-field indentation rules