fix: fake client targeting and harden client state resets

[Rushaway]

Description

This PR fixes a runtime exception in ThirdPerson when a fake client is processed during spawn/death flow and eventually reaches camera/convar code paths.

Context

A server error was reported:

• Client X is fake and cannot be targeted
• Exception on SendConVarValue from MirrorOff
• Call path triggered from player_spawn -> ResetClient -> MirrorOff

L 03/27/2026 - 07:11:49: [SM] Exception reported: Client 6 is fake and cannot be targeted
L 03/27/2026 - 07:11:49: [SM] Blaming: custom/ThirdPerson.smx
L 03/27/2026 - 07:11:49: [SM] Call stack trace:
L 03/27/2026 - 07:11:49: [SM]   [0] SendConVarValue
L 03/27/2026 - 07:11:49: [SM]   [1] Line 304, ThirdPerson/addons/sourcemod/scripting/ThirdPerson.sp::MirrorOff
L 03/27/2026 - 07:11:49: [SM]   [2] Line 250, ThirdPerson/addons/sourcemod/scripting/ThirdPerson.sp::ResetClient
L 03/27/2026 - 07:11:49: [SM]   [3] Line 202, ThirdPerson/addons/sourcemod/scripting/ThirdPerson.sp::Event_PlayerSpawn
L 03/27/2026 - 07:11:49: [SM]   [5] CreateFakeClient
L 03/27/2026 - 07:11:49: [SM]   [6] Line 115, FakeClients/addons/sourcemod/scripting/FakeClients.sp::Timer_CreateFakeClient

Root cause

Two logic issues made fake clients reachable in reset paths:

1. Spawn validation was too permissive for bots in the current helper semantics.
2. Death condition precedence allowed state-reset logic to run in edge cases where the client validity guard was not applied as intended.

What changed

• Tightened the death condition with explicit parentheses so client validity always gates mirror/thirdperson checks.
• Updated spawn validation to exclude fake clients before calling reset logic.
• Added disconnect cleanup to always clear thirdperson/mirror flags when a slot is released.

Behavior impact

• Fake clients are no longer sent client-targeted convar updates.
• Human players keep the same expected behavior.
• State is cleaner across disconnect/reconnect cycles.

Test plan

1. Load ThirdPerson and FakeClients plugins.
2. Spawn fake clients repeatedly.
3. Trigger player_spawn and player_death events for fake and real clients.
4. Verify no SourceMod exception about fake client targeting appears.
5. Confirm real clients can still toggle mirror/thirdperson normally.

Risk

Low. Changes are scoped to validation/guard logic and state reset paths.

[Copilot]

Pull request overview

This PR hardens ThirdPerson’s client validation and state-reset paths to prevent runtime exceptions when fake clients hit spawn/death flows that ultimately call client-targeted ConVar updates.

Changes:

• Bumped plugin version to 1.3.6.
• Fixed operator-precedence in Event_PlayerDeath so client validity properly gates mirror/thirdperson reset logic.
• Tightened spawn validation and added disconnect cleanup to clear per-client thirdperson/mirror state when slots are released.