Make the repository pages reviewable in development

`/{owner}/{repo}` was a 404 on every development machine, for every
repository, because the forge is off in the base config -- `forge_data_dir`
defaults to `/var/lib/openagents/forge`, which a laptop cannot write. So the
repository surfaces could not be looked at locally at all. Dev now enables the
forge against a directory inside the checkout, which is ignored.

The commit and diff pages still need that storage populated, so they stay 404
locally until a repository is actually mirrored there; the repository page
itself renders.

Also drops a tautological assertion from the changelog tests. Comparing a list
of literals to `[]` is a comparison between distinct types, always false, and
it broke `mix precommit`, which is `--warnings-as-errors`.

Deploy story

What this commit did to the running system — joined from the forge receipt chain, the part a commit page elsewhere cannot show.

Changed files

• modified .gitignore
• modified config/dev.exs
• modified test/openagents/changelog_test.exs

Diff

3 files changed, +12 -1

# Local environment variables

/.env

# Local development forge storage (config/dev.exs points at it).

/.local/

# path, and a write that escapes the sandbox is a flaky suite.

config :openagents, :changelog_backfill_on_boot, true

# The forge, pointed at a writable directory inside the checkout. It is off in

# the base config because `forge_data_dir` defaults to `/var/lib`, which no

# development machine can write -- and with it off, every `/{owner}/{repo}`

# page is a 404 locally, so the repository surfaces cannot be reviewed at all.

config :openagents,

  forge_enabled: true,

  forge_data_dir: Path.expand("../.local/forge", __DIR__)

# Configure your database

config :openagents, OpenAgents.Repo,

  username: System.get_env("USER") || "christopherdavid",

      # They are anchored to the history that preceded this repository's

      # clean-room rewrite. Kept so they can be restored if that history is

      # ever grafted in; not seeded, because today they would be dead links.

      refute Backfill.pre_public_entries() == []

      refute Enum.empty?(Backfill.pre_public_entries())

      seeded = MapSet.new(Backfill.seeded_entries(), & &1.sha)