Bump mojo-regex from 0.10.0 to 0.21.0

[msaelices]

Updates the mojo-regex recipe to v0.21.0 (pinned to ce1be86).

Changes

• context.version: 0.10.0 -> 0.21.0
• context.mojo_version: =0.26.2 -> =1.0.0b3.dev2026062806 (matches the project's pixi.toml pin; the codebase has been migrated through the 1.0.0b1/b2/b3 breaking changes, including the AnyOrigin -> UntrackedOrigin origin-model migration, and requires this nightly)
• source[0].rev: pinned to the v0.21.0 release commit
• Description refreshed: current benchmark win rates (97% vs Python re, 83% vs Rust regex, from the repo's benchmarks/results/comparison.md) and a note on the new compile-time pattern specialization feature.

Highlights since 0.10.0

• Compile-time pattern specialization (new in 0.21.0): pass the pattern as a comptime parameter (search["hello"](text)) and the parser + DFA compiler run inside Mojo's comptime interpreter, embedding the automaton in the binary: no runtime compilation, no per-call pattern hash or cache probe, and invalid patterns fail the build.
• Compiler-tracked match lifetimes: Match[origin] is parameterized on the backing-text origin end to end.
• Mojo 1.0.0b3 nightly compatibility, zero compiler warnings, 389 tests.
• Numerous SIMD hot-path optimizations (two-byte memchr-style literal scan, bounds-check recovery under 1.0.0b1).

Supersedes #264.

[msaelices]

Thanks for the "OK to test" label. The arm failure was the short commit SHA in source[0].rev (GitHub only serves full SHAs to git fetch); fixed by pinning the full 40-char SHA.

Heads-up on the next run: the build will likely fail resolving mojo-compiler =1.0.0b3.dev2026062806. mojo-regex 0.21.0 requires the 1.0.0b3 origin model (UntrackedOrigin), which is currently nightly-only, and this repo builds against the stable max channel (tops out at 1.0.0b2 today). I will update the pin to =1.0.0b3 as soon as the stable b3 ships; feel free to leave this PR parked until then.