Make opt-level=1 the default for tests

[hildebrandmw]

Our workspace-wide tests have been pretty useless to run at opt-level=0 (the default for the dev/test) for a while now. This was made worse by the addition of larger testing datasets.

To tackle this, the ci profile was introduced to build and run our tests at opt-level=1.

However, as the workspace continues to grow, opt-level=1 more and more just needs to be the default. Especially to be compatible with crater runs.

This PR drops the ci profile and instead changes our profile.test to use opt-level=1 by default. After this PR,

cargo nextest run --workspace

will use opt-level=1 and behave like our current

cargo nextest run --workspace --cargo-profile ci

[Copilot]

Pull request overview

This PR removes the custom ci Cargo profile and makes opt-level = 1 the workspace default for tests by configuring profile.test. This keeps debug assertions/overflow checks (via test inheriting from dev) while significantly improving end-to-end test runtime, aligning local cargo test/cargo nextest behavior with prior CI behavior.

Changes:

• Drop the [profile.ci] profile and set [profile.test] opt-level = 1 workspace-wide.
• Update CI and nightly workflows to stop using --profile ci / --cargo-profile ci.
• Update developer docs/scripts (diskann-wide docs + agents.md) to remove ci profile references.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
diskann-wide/README.md	Removes --profile ci from test instructions so defaults use profile.test opt-level=1.
diskann-wide/compile-aarch64-on-x86.sh	Removes --profile ci so cross-test uses the new default test profile.
Cargo.toml	Deletes profile.ci and sets profile.test.opt-level = 1 with rationale/commentary.
agents.md	Updates repository/testing guidance to reflect test profile (removes ci references).
.github/workflows/nightly.yml	Removes --cargo-profile ci / --profile ci usage so nightly runs use default test profile.
.github/workflows/ci.yml	Removes ci profile usage across jobs; switches clippy/build steps to --profile test where a profile is explicitly chosen.

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[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.00%. Comparing base (ee7dbaa) to head (4e5e63a).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1235      +/-   ##
==========================================
- Coverage   91.01%   90.00%   -1.02%     
==========================================
  Files         501      501              
  Lines       95572    95572              
==========================================
- Hits        86988    86018     -970     
- Misses       8584     9554     +970     

Flag	Coverage Δ
miri	90.00% <ø> (-1.02%)	⬇️
unittests	89.66% <ø> (-1.32%)	⬇️

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