One-Day cTBS Over the Precuneus

The goal of this clinical trial is to learn whether two forms of one-day accelerated transcranial magnetic stimulation (TMS) can reduce depressive symptoms in adults with treatment-resistant depression. Treatment-resistant depression is depression that has not improved enough after at least two adequate antidepressant medication treatments. TMS is a non-invasive treatment that uses magnetic pulses to stimulate specific areas of the brain. The main questions this study aims to answer are: * Does continuous theta-burst stimulation (cTBS) targeting the precuneus reduce depressive symptoms 4 weeks after treatment compared with sham stimulation? * Does intermittent theta-burst stimulation (iTBS) targeting the left dorsolateral prefrontal cortex reduce depressive symptoms 4 weeks after treatment compared with sham stimulation? Researchers will compare precuneus cTBS, left dorsolateral prefrontal cortex iTBS, and sham stimulation to determine whether either active treatment reduces depressive symptoms more than sham stimulation. Participants will be randomly assigned to one of the three groups and will not be told which treatment they initially receive. Participants will: * Complete screening procedures and baseline assessments of depression, rumination, and cognitive function * Receive 20 sessions of active or sham TMS during one in-person study day * Complete follow-up assessments 1, 2, 3, and 4 weeks after the intervention * Report any side effects or medical problems experienced during the study Participants initially assigned to sham stimulation may choose to receive active TMS after completing the 4-week follow-up period. Those who choose this option will receive either precuneus cTBS or left dorsolateral prefrontal cortex iTBS and will complete additional follow-up assessments.