harden(protocol): bound + charset-constrain the handshake session_id … #1151

Job	Run time
Python 3.13 / ubuntu-latest	4m 2s
Stale server smoke / Windows	2m 31s
Game capture smoke / macOS	2m 9s
Release smoke / ubuntu-latest	44s
Release smoke / windows-latest	1m 24s
Godot tests / Linux	1m 11s
Godot tests / Linux (Godot 4.3)	1m 17s
Game capture smoke / Windows	1m 53s
Release smoke / macos-latest	39s
Stale server smoke / macOS	45s
Stale server smoke / Linux	32s
Game capture smoke / Linux	1m 7s
Godot tests / Windows	2m 43s
Python 3.11 / ubuntu-latest	2m 0s
Godot tests / macOS	1m 25s
	24m 22s

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