Add perception-aware lattice A* planning (transplant from mad_demo)

[nehirgerek]

Brings the perception-aware global planner onto the dev-rr-mad-eth-elevation branch. Plans a heading-lattice A* over the tristate belief (FREE/OCC/UNK) under a sensor-coverage invariant: an unknown cell may only be traversed if it was (or will be) observed from the primitive start pose or a back-projected virtual pose (Livox Mid-360 tilted-ground FOV model). Enabled per-config for ground-robot 2D planning via perception_aware_planning; otherwise a no-op.

Contents:

• perception_planner.{hpp,cpp}: sensor models (Mid360FOV, AnnulusSensor), motion primitives, memoized Amanatides-Woo visibility, lattice A* with timeout/max-expand guards and best-node partial recovery, ladder-based coverage audit (diagnostic).
• hgp_planner: configurePerceptionAware() + planPerceptionAware(); plan() routes through it when enabled. Fail-stop: never falls back to grid A*; rejects the replan (robot holds) when the belief is not ready or not in 2D mode. Partial paths gated on >= ~1 cell net progress; partial-ness exposed via getters and logged.
• hgp_manager / mighty_type / mighty_node / config: plumb the enable flag and hand the planner the tristate belief + robot radius.
• scripts/diag_grid_test.py, scripts/mid360_fov_viz.py, launch/diag_test.launch.py, rviz overlay: RViz test harness and FOV visualization.

Merge notes: transplanted onto the diverged eth-elevation line; only CMakeLists.txt conflicted (union of installed scripts). The graph_search diagonal corner-cut fix was already present on this branch.

NOTE: NOT yet compiled or run in sim on this branch. A colcon build, frontier-start sim validation, and confirmation that the Mid-360 extrinsics match the real rover are all still outstanding before any rover deployment.