Breakpoints silently no-op without -debugger (Lua API and GDB stub)

Running headless with `-dofile`, breakpoints set via `PCSX.addBreakpoint` never fire. `addBreakpoint` returns a valid object and raises no error, but the callback is never invoked — verified both on the game's per-frame loop and on the BIOS reset vector at `0xBFC00000`, which unquestionably executes. `PCSX.nextTick` also never fires in this mode.

The same applies to the GDB stub. `Z0`–`Z4` all reply `OK`, but no breakpoint or watchpoint ever triggers. Notably `qSupported` advertises `PacketSize`, `qXfer:*` and `QStartNoAckMode` — but neither `swbreak+` nor `hwbreak+`.

Adding `-debugger` fixes both immediately: Lua callbacks fire, and GDB watchpoints trigger correctly.

This is reasonable behaviour, but it's undiscoverable. The CLI docs describe `-debugger` as "Activates the debugger" without indicating that breakpoints are inert without it, and a stub answering `OK` to `Z` packets it then ignores is hard to distinguish from a target where the breakpoint simply hasn't been hit yet.

Suggestions, in rough order of value:

- Mention the `-debugger` dependency in the Lua and CLI docs
- Have the GDB stub return an empty reply (the RSP convention for "unsupported") for `Z` packets when the debugger is inactive
- Optionally log a warning when `addBreakpoint` is called with the debugger off

One caveat for completeness: I did not test whether Lua breakpoints work *with* `-debugger` in headless mode specifically — I confirmed GDB watchpoints do and moved on. The `qSupported` observation and the docs gap stand regardless.

Version: nightly build 360 (24892.20260724.3, x64), Windows, interpreter core.

Reproduce the headless `-dofile` case, then trace the Lua breakpoint/`nextTick` entry points and the GDB stub's `Z0`–`Z4` handling, comparing both with `-debugger` enabled. Done means the Lua and CLI documentation states the dependency and the stub's inactive-debugger behavior is made explicit and covered by the relevant checks.

Written by the indexing model from the issue text.