A series of fixes in stage

[ryanjjung]

A few things are present in this PR, all related to our stage environment:

• Added back some environment secrets that had been inadvertently removed, leading to database connection errors.
• Removed some instructions in the readme that I suspect are old because they have been resolved in the compose file and doing what the readme says actually breaks my local dev setup.
• Added instructions to the readme on accessing the Flower web interface.
• Updated the compose file to include some file watches on the accounts service since testing changes to my env was otherwise quite slow.
• Added a new optional environment variable called SENTRY_TRACES_SAMPLE_RATE, which defaults to 0.0. This value should be a float between 0.0 and 1.0 indicating a percentage of application traces to send to Sentry. At 1.0, this is 100% of all traces (which can be a lot).
• Updated stage services to define different trace sample rates, trying to quiet some of the health check noise from Flower.
• Enabled FLOWER_UNAUTHENTICATED_API in Flower, which makes the UI fully functional. This is discouraged, and we don't have auth set up here, but it should be okay since we have to have infra-level permissions to build a bastion to SSH proxy our way in. We should revisit this auth later in the context of other queue functions we have and the idea we've been throwing around of setting up a central Keycloak auth server for corporate systems.
• Out of habit, I ran a uv run ruff format, which produced a number of lint updates.

[MelissaAutumn]

Did I break this in the rebase fix? It was without the env at the end.

[ryanjjung]

I'm not certain if/where it broke. There was a point when I did not use the env name suffix, but we definitely need it now. I will pull your changes and do a quick pulumi preview to see if anything odd is there. brb

[MelissaAutumn]

Looks good, but prod changes will cause no sentry traces to be sent. Might want to correct that.

[ryanjjung]

I ran these task definition changes out to the environment. When the new code gets deployed, the settings should be there to take effect.