Description

Add an interrupt vector table so AstraKernel can handle exceptions and interrupts in a structured way. This is the foundation for adding timer interrupts, fault handling, and later context switching.

Tasks

• Define vector table layout in assembly start.s.
• Add default handlers (reset, undefined instruction, software interrupt, prefetch abort, data abort, IRQ, FIQ).
• Implement a generic default_handler that just loops/hangs for now.
• Hook the reset entry to _start.
• Update linker script if necessary to make sure the vector table is at the correct memory address.
• Document the memory addresses and behavior of each vector entry.

Acceptance Criteria

• Kernel builds with the vector table placed correctly.
• On startup, the system jumps to _start via the reset vector.
• Any unexpected exception should land in default_handler.
• Verified in QEMU that the kernel still boots with the vector table in place.