feat(fault_pack): promote /rosout WARN+/ERROR/FATAL to faults

[mfaferek93]

Brownfield robots emit no structured faults but every node logs to /rosout. Promote selected log entries to FaultManager faults, attributed to the originating node, with zero changes to the publisher.

Scope

• Subscribe /rosout (rcl_interfaces/msg/Log).
• Level mapping: WARN -> SEVERITY_WARN, ERROR -> SEVERITY_ERROR, FATAL -> SEVERITY_CRITICAL; INFO/DEBUG dropped. Configurable severity_floor (default WARN). ERROR/FATAL confirm immediately; WARN lands PREFAILED when confirmation_threshold <= -2.
• source_id = node FQN: prepend /, strip sub-logger suffix after . (controller_manager.resource_manager -> /controller_manager). Required so faults associate with runtime-discovered entities and their snapshots route in the UI.
• fault_code auto-generated and stable across occurrences (node + normalized message template: digits/hex/paths stripped, hashed).
• Per-node reporter (own debounce); exclude own logs; include_only_nodes / exclude_nodes filters.

Acceptance

• A node logging RCLCPP_ERROR yields a CONFIRMED fault in list_faults with source = that node FQN.
• GET /api/v1/apps/<node>/faults returns the fault, and its rosbag/snapshot is reachable via the entity bulk-data path.
• WARN appears as PREFAILED under confirmation_threshold <= -2.
• Unit tests: level -> severity mapping, fault_code generation/stability, source_id normalization.