## Problem
Integration keys (`fugitive`, `neogit`, `gitsigns`, `committia`,
`telescope`)
live at the top level of `vim.g.diffs`, cluttering the config namespace.
## Solution
Move them under `vim.g.diffs.integrations.*`. Old top-level keys still
work but
emit `vim.deprecate` targeting v0.3.2. `compute_filetypes` and
`plugin/diffs.lua`
fall back to legacy keys for pre-`init()` callers.
Also includes `83c17ac` which fixes an invalid hex hash in the combined
diff test
fixture.
## Problem
Users had to pass `enabled = true` or `enabled = false` inside
fugitive/neogit config tables, which was redundant — table presence
already implied the integration should be active.
## Solution
Remove the `enabled` field from the public API. Table presence now
implies enabled, `false` disables, `true` expands to sub-defaults.
The `enabled` field is still accepted for backward compatibility.
Added 20 `compute_filetypes` tests covering all config shapes (true,
false, table, nil, backward-compat enabled field). Updated docs
and type annotations.
