Add compact telemetry schema V2 for storage efficiency

[Copilot]

Introduces a V2 telemetry schema to address storage inefficiencies (60-80% reduction expected) while preserving wire compatibility with existing V1 format.

Changes

New proto file: proto/telemetry/v1/telemetry_compact.proto

• EnvelopeV2 - Streaming wrapper for V2 messages
• TelemetryHeaderV2 - base_time_unix_nanos + typed metadata (server_id, mode, level); deltas from base per-frame instead of repeated Timestamp
• SessionStatic - Rarely-changing session data (session_id, map_name, client_name) moved from per-frame to header
• LobbySessionStateFrameV2 - sint32 delta_nanos from base time (±2.1s range, ~11ms/frame typical)
• CompactSessionState - float32 with packed encoding for all vectors (disc position/velocity, game state); enums for pause_state and match_type
• CompactTeam/Player/Stats - Float32 transforms (head/body/hand pos/forward/left/up), all vectors length-3 validated
• CompactPlayerBones - Keyframe interval + delta frames; changed_mask bitmask (little-endian bit ordering); translations (3×N floats), orientations (4×N quaternions)

Storage Impact

Optimization	V1	V2
Time per frame	Timestamp (10+ bytes)	sint32 delta (1-5 bytes)
Vectors	double (8 bytes × 3)	float packed (4 bytes × 3)
Enums	string (5-20 bytes)	varint (1-2 bytes)
Bones	Full per frame	Keyframe + delta + mask

Usage

// Producer
TelemetryHeaderV2 {
  capture_id: "uuid"
  base_time_unix_nanos: 1703001234000000000
  timestep_nanos: 11111111  // 90 Hz
  static: { session_id: "...", map_name: "arena", match_type: ARENA_PUBLIC }
}

LobbySessionStateFrameV2 {
  frame_index: 42
  // delta_nanos omitted when fixed timestep
  session: { disc_position: [0.0, 1.5, 0.0], ... }
  player_bones: { frame_modulus: 5, frames: [...] }
}

Wire Compatibility

Existing Envelope, TelemetryHeader, LobbySessionStateFrame remain unchanged. Consumers can adopt V2 progressively alongside V1.

Out of Scope

• rtapi integration (future PR)
• int16/int24 quantization (future PR)
• Weapon/ordnance enum tables (future PR)

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Original prompt

Goal
Add a compact telemetry schema (V2) alongside existing telemetry to
address storage inefficiencies without breaking wire compatibility.

Primary inefficiencies observed

• Per-frame google.protobuf.Timestamp repeated in every
  LobbySessionStateFrame. Solution: base time in header + per-frame delta
  varint.
• Full enginehttp.SessionResponse embedded per frame; many fields are
  static or infrequently changing. Solution: split static vs dynamic;
  static in header; dynamic in frames; or use change events.
• Orientation/position/velocity stored as repeated double (64-bit).
  Solution: float32 and/or quantization (packed repeated) in compact
  messages.
• String enums (paused_state, team, goal_type, match_type, map_name,
  team_name, weapon/ordnance/tac_mod, etc.). Solution: enums or ID table
  in header.
• Player bones repeated fully per frame. Solution: keyframe + delta frames
  with bitmask of changed indices; store float32.
• Metadata map in header has overhead. Solution: promote common keys to
  typed fields and keep a small extra map.

Scope of this PR

• Introduce a new proto file with V2 compact messages. Do not modify tag
  numbers of existing messages. Keep existing telemetry intact.
• Provide EnvelopeV2 which carries TelemetryHeaderV2 and
  LobbySessionStateFrameV2.
• Compact representations for session state, teams, players, stats, and
  bones.
• No runtime integration changes in rtapi yet; producers/consumers can
  adopt V2 progressively.

Acceptance criteria

• New proto file compiles with protoc (no build breakage in repo).
• Messages include documentation for migration.
• Wire compatibility preserved: existing telemetry remains untouched.

Proposed changes (new file)

syntax = "proto3";
package telemetry.v1;

import "google/protobuf/timestamp.proto"; // kept for possible interop

option csharp_namespace = "Nevr.Telemetry.Protobuf";
option go_package = "github.com/echotools/nevr-common/v4/gen/go/telemetry/v1;telemetry";
option java_multiple_files = true;
option java_outer_classname = "NevrTelemetryCompact";
option java_package = "com.echotools.nevr.telemetry.v1";

// EnvelopeV2 wraps compact telemetry messages for streaming.
message EnvelopeV2 {
  oneof message {
    TelemetryHeaderV2 header = 1;
    LobbySessionStateFrameV2 frame = 2;
  }
}

// Compact header: base time + typed metadata; small extra map
message TelemetryHeaderV2 {
  string capture_id = 1;
  uint64 base_time_unix_nanos = 2;   // replaces created_at
  uint32 timestep_nanos = 3;         // fixed step (optional)
  uint64 server_id = 4;              // promoted metadata
  string mode = 5;                   // promoted metadata
  string level = 6;                  // promoted metadata
  map<string,string> extra = 7;      // remaining metadata
  SessionStatic static = 8;          // session strings that rarely change
}

message SessionStatic {
  string session_id = 1;
  string map_name = 2;
  MatchType match_type = 3;
  string client_name = 4;
}

enum MatchType {
  MATCH_TYPE_UNSPECIFIED = 0;
  MATCH_TYPE_ARENA_PUBLIC = 1;
  MATCH_TYPE_ARENA_PRIVATE = 2;
  MATCH_TYPE_COMBAT_PUBLIC = 3;
  MATCH_TYPE_COMBAT_PRIVATE = 4;
}

// Compact frame: delta time + compact session + compact bones
message LobbySessionStateFrameV2 {
  uint32 frame_index = 1;
  // varint delta from base_time; omit when derivable from frame_index
  sint32 delta_nanos = 2;
  repeated LobbySessionEvent events = 3; // reuse existing event types
  CompactSessionState session = 4;
  CompactPlayerBones player_bones = 5;
}

// Compact session replaces repeated double with float, strings with enums
message CompactSessionState {
  // Disc
  repeated float disc_position = 1;  // len=3, packed
  repeated float disc_forward = 2;   // len=3, packed
  repeated float disc_left = 3;      // len=3, packed
  repeated float disc_up = 4;        // len=3, packed
  repeated float disc_velocity = 5;  // len=3, packed

  // Teams
  repeated CompactTeam teams = 10;

  // Pause
  PauseStateEnum pause_state = 20;
  float paused_timer = 21;
  float unpaused_timer = 22;

  // Game clock + payload
  float game_clock = 30;
  float payload_multiplier = 31;
  float payload_distance = 32;
  float payload_speed = 33;
  int32 payload_checkpoint = 34;
  uint32 blue_points = 35;
  uint32 orange_points = 36;
}

enum PauseStateEnum {
  PAUSE_STATE_UNSPECIFIED = 0;
  PAUSE_STATE_PAUSED = 1;
  PAUSE_STATE_UNPAUSED = 2;
  PAUSE_STATE_PENDING = 3;
}

message CompactTeam {
  uint32 team_id = 1;        // enum or small ID
  bool has_possession = 2;
  CompactTeamStats stats = 3;
  repeated CompactPlayer players = 4;
}

message CompactTeamStats {
  float possession_time = 1;
  uint32 points = 2;
  uint32 saves = 3;
  uint32 goals = 4;
  uint32 stuns = 5;
  uint32 passes = 6;
  uint32 catches = 7;
  uint32 steals = 8;
  uint32 blocks = 9;
  uint32 interceptions = 10;
  uint32 assists = 11;
  uint32 shots_taken = 12;
}

message CompactPlayer {
  ...

</details>



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