sv_pure 1 and 2 works, no non-native CRCs are allowed

[blaberry]

[kassibuss]

Just to consider for what sv_pure should ignore(?), as of the last tournament (WW2025), the player is allowed to edit the following sounds/vtfs:

• Round win/tie jingles
• Weapon kill icons
• Capture point beacons
• Ghost beacon
• Weapon images on the loadout screen
• Round end overlays (the JINRAI WINS/NSF WINS/TIE overlay)
• Kill icons
• Crosshairs (the regular and FF warning crosshair)

Maybe sv_pure should also ignore the weapon sounds, since some players have their own custom sounds

[Rainyan]

Related: #1053 - Assets (likely, I haven't investigated this too much?) should be packed into VPK post-SteamPipe if we want to use sv_pure on them). Unless we roll something completely custom. But in any case, it's a good idea for disk I/O perf reasons to hash file archives instead of individual files.