refactor: extract spline math, consolidate packet parsing, decompose TransportManager

Extract CatmullRomSpline (include/math/spline.hpp, src/math/spline.cpp) as a
standalone, immutable, thread-safe spline module with O(log n) binary segment
search and fused position+tangent evaluation — replacing the duplicated O(n)
evalTimedCatmullRom/orientationFromTangent pair in TransportManager.

Consolidate 7 copies of spline packet parsing into shared functions in
game/spline_packet.{hpp,cpp}: parseMonsterMoveSplineBody (WotLK/TBC),
parseMonsterMoveSplineBodyVanilla, parseClassicMoveUpdateSpline,
parseWotlkMoveUpdateSpline, and decodePackedDelta. Named SplineFlag constants
replace magic hex literals throughout.

Extract TransportPathRepository (game/transport_path_repository.{hpp,cpp}) from
TransportManager — owns path data, DBC loading, and path inference. Paths stored
as PathEntry wrapping CatmullRomSpline + metadata (zOnly, fromDBC, worldCoords).
TransportManager reduced from ~1200 to ~500 lines, focused on transport lifecycle
and server sync.

Signed-off-by: Pavel Okhlopkov <pavel.okhlopkov@flant.com>

include/game/spline_packet.hpp

@@ -0,0 +1,108 @@
+// include/game/spline_packet.hpp
+// Consolidated spline packet parsing — replaces 7 duplicated parsing locations.
+#pragma once
+#include "network/packet.hpp"
+#include <glm/glm.hpp>
+#include <vector>
+#include <cstdint>
+
+namespace wowee::game {
+
+/// Decoded spline data from a movement or MonsterMove packet.
+struct SplineBlockData {
+    uint32_t splineFlags = 0;
+    uint32_t duration = 0;
+
+    // Animation (splineFlag 0x00400000)
+    bool     hasAnimation = false;
+    uint8_t  animationType = 0;
+    uint32_t animationStartTime = 0;
+
+    // Parabolic (splineFlag 0x00000800 for MonsterMove, 0x00000008 for MoveUpdate)
+    bool     hasParabolic = false;
+    float    verticalAcceleration = 0.0f;
+    uint32_t parabolicStartTime = 0;
+
+    // FINAL_POINT / FINAL_TARGET / FINAL_ANGLE (movement update only)
+    bool     hasFinalPoint = false;
+    glm::vec3 finalPoint{0};
+    bool     hasFinalTarget = false;
+    uint64_t finalTarget = 0;
+    bool     hasFinalAngle = false;
+    float    finalAngle = 0.0f;
+
+    // Timing (movement update only)
+    uint32_t timePassed = 0;
+    uint32_t splineId = 0;
+
+    // Waypoints (server coordinates, decoded from packed-delta if compressed)
+    std::vector<glm::vec3> waypoints;
+    glm::vec3 destination{0};
+    bool hasDest = false;
+
+    // SplineMode (movement update WotLK only)
+    uint8_t splineMode = 0;
+    glm::vec3 endPoint{0};
+    bool hasEndPoint = false;
+};
+
+// ── Spline flag constants ───────────────────────────────────────
+namespace SplineFlag {
+    constexpr uint32_t FINAL_POINT    = 0x00010000;
+    constexpr uint32_t FINAL_TARGET   = 0x00020000;
+    constexpr uint32_t FINAL_ANGLE    = 0x00040000;
+    constexpr uint32_t CATMULLROM     = 0x00080000; // Uncompressed Catmull-Rom
+    constexpr uint32_t CYCLIC         = 0x00100000; // Cyclic path
+    constexpr uint32_t ENTER_CYCLE    = 0x00200000; // Entering cyclic path
+    constexpr uint32_t ANIMATION      = 0x00400000; // Animation spline
+    constexpr uint32_t PARABOLIC_MM   = 0x00000800; // Parabolic in MonsterMove
+    constexpr uint32_t PARABOLIC_MU   = 0x00000008; // Parabolic in MoveUpdate
+
+    // Mask: if any of these are set, waypoints are uncompressed
+    constexpr uint32_t UNCOMPRESSED_MASK = CATMULLROM | CYCLIC | ENTER_CYCLE;
+    // TBC-era alternative for uncompressed check
+    constexpr uint32_t UNCOMPRESSED_MASK_TBC = CATMULLROM | 0x00002000;
+} // namespace SplineFlag
+
+/// Decode a single packed-delta waypoint.
+/// Format: bits [0:10] = X (11-bit signed), [11:21] = Y (11-bit signed), [22:31] = Z (10-bit signed).
+/// Each component is multiplied by 0.25 and subtracted from `midpoint`.
+[[nodiscard]] glm::vec3 decodePackedDelta(uint32_t packed, const glm::vec3& midpoint);
+
+/// Parse a MonsterMove spline body (after splineFlags has already been read).
+/// Handles: Animation, duration, Parabolic, pointCount, compressed/uncompressed waypoints.
+/// `startPos` is the creature's current position (needed for packed-delta midpoint calculation).
+/// `splineFlags` is the already-read spline flags value.
+/// `useTbcUncompressedMask`: if true, use 0x00080000|0x00002000 for uncompressed check (TBC format).
+[[nodiscard]] bool parseMonsterMoveSplineBody(
+    network::Packet& packet,
+    SplineBlockData& out,
+    uint32_t splineFlags,
+    const glm::vec3& startPos,
+    bool useTbcUncompressedMask = false);
+
+/// Parse a MonsterMove spline body where waypoints are always compressed (Vanilla format).
+/// `startPos` is the creature's current position.
+[[nodiscard]] bool parseMonsterMoveSplineBodyVanilla(
+    network::Packet& packet,
+    SplineBlockData& out,
+    uint32_t splineFlags,
+    const glm::vec3& startPos);
+
+/// Parse a Classic/Turtle movement update spline block.
+/// Format: splineFlags, FINAL_POINT/TARGET/ANGLE, timePassed, duration, splineId,
+/// pointCount, uncompressed waypoints (12 bytes each), endPoint (no splineMode).
+[[nodiscard]] bool parseClassicMoveUpdateSpline(
+    network::Packet& packet,
+    SplineBlockData& out);
+
+/// Parse a WotLK movement update spline block.
+/// Format: splineFlags, FINAL_POINT/TARGET/ANGLE, timePassed, duration, splineId,
+/// then WotLK header (durationMod, durationModNext, [Animation], [Parabolic],
+/// pointCount, splineMode, endPoint) with multi-strategy fallback.
+[[nodiscard]] bool parseWotlkMoveUpdateSpline(
+    network::Packet& packet,
+    SplineBlockData& out,
+    const glm::vec3& entityPos = glm::vec3(0));
+
+} // namespace wowee::game