chore(deps): update cargo dependencies

[tclem]

Updates rand and rand_chacha from 0.9 to 0.10 across all workspace crates. Both are major version bumps but the blast radius is limited -- rand is only used in test helpers, benchmarks, and behind an optional feature flag in bpe.

Updated packages

Package	Old	New	Crates affected
rand	0.9	0.10	bpe, geo_filters, string-offsets, bpe-tests, bpe-benchmarks
rand_chacha	0.9	0.10	geo_filters, string-offsets

Code changes

rand 0.10 reorganized its trait hierarchy, requiring updates to imports and trait bounds across 8 source files:

• random() and random_range() moved from Rng to a new RngExt trait
• The base trait was renamed from RngCore to Rng in rand_core
• RngCore is no longer re-exported from the rand crate
• StdRng::from_os_rng() was removed in favor of rand::make_rng()

Validation

• make lint -- passes (fmt + clippy)
• make test -- all tests pass
• make build -- full workspace build succeeds

Supersedes #100 and #101.

[Copilot]

Pull request overview

Updates the workspace to rand/rand_chacha 0.10 and applies the corresponding API migrations (trait renames, RNG construction helpers) across library code, tests, and benchmarks.

Changes:

• Bump rand and rand_chacha from 0.9 to 0.10 in affected crates.
• Update RNG-related imports and trait bounds to match rand 0.10 (RngExt, rand::make_rng(), rand::Rng for next_u64()-style APIs).
• Adjust test/benchmark code to compile against the new rand API surface.

Reviewed changes

Copilot reviewed 14 out of 14 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
crates/string-offsets/benchmarks/performance.rs	Switches benchmark RNG trait import to RngExt for random_range().
crates/string-offsets/Cargo.toml	Updates dev-dependency versions for rand and rand_chacha.
crates/geo_filters/src/evaluation/simulation.rs	Updates rand trait import and replaces StdRng::from_os_rng() with rand::make_rng().
crates/geo_filters/src/distinct_count.rs	Updates test-only RNG trait import to the new rand::Rng (aliased).
crates/geo_filters/src/diff_count.rs	Updates RNG trait imports in test-support code and tests for rand/rand_chacha 0.10.
crates/geo_filters/src/config/lookup.rs	Updates test-only RNG trait import to the new rand::Rng (aliased).
crates/geo_filters/src/config.rs	Updates test-only RNG trait import to the new rand::Rng (aliased).
crates/geo_filters/Cargo.toml	Updates optional + dev dependency versions for rand and rand_chacha.
crates/bpe/tests/src/lib.rs	Updates tests to use RngExt for random_range().
crates/bpe/tests/Cargo.toml	Updates rand dev-dependency to 0.10.
crates/bpe/src/byte_pair_encoding.rs	Migrates rand usage to RngExt and updates the public encode_minimal_dropout bound accordingly.
crates/bpe/benchmarks/performance.rs	Updates benchmark RNG usage to RngExt and removes now-unneeded imports.
crates/bpe/benchmarks/Cargo.toml	Updates rand benchmark dependency to 0.10.
crates/bpe/Cargo.toml	Updates optional rand dependency to 0.10.

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