chore: lint fixes part 3

[pawbana]

• receiver-naming (7): standardized receiver names to be consistent within each type (i for interception types)
• unused-receiver (34): omitted unused receiver names on methods that don't reference the receiver (e.g. Streaming(), Type(), AuthHeader(), encodeForStream(), etc.)
• unused-parameter (11): renamed unused ctx to _ in mock recorders, MCP proxy shutdown, and async recorder; renamed unused w to _ in CreateInterceptor; renamed unused ctx to _ in mock MCP tool callback
• unused field (1): removed unused closeOnce sync.Once field from eventstream

[pawbana]

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• feat: add lint check to CI cheks #263
• chore: lint fixes part 10 #262
• chore: lint fixes part 9 #261
• chore: lint fixes part 8 #260
• chore: lint fixes part 7 #259
• chore: lint fixes part 6 #258
• chore: lint fixes part 5 #257
• chore: lint fixes part 4 #256
• chore: lint fixes part 3 #255 👈 (View in Graphite)
• chore: lint fixes part 2 #254
• chore: lint fixes part 1 (automatic fixes) #253
• feat: extend golang lint check #252
• main

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