Preserve additional_dependencies order and use synthetic local repo for local hooks

[shaanmajid]

Summary

• Replace FxHashSet<String> with Vec<String> for additional_dependencies throughout the codebase, preserving user-specified ordering and duplicates. This matches pre-commit semantics and fixes hooks that
  pass non-dependency arguments (e.g., --index-url <url>) in additional_dependencies.
• For repo: local Python hooks with additional_dependencies, install from a synthetic placeholder repository (matching pre-commit's pre-commit-placeholder-package) instead of the project root. This prevents
  . from depending on user project contents.

Closes #1602
Closes #1603

Notes

• Existing cached hook environments will be re-created on upgrade due to the FxHashSet → Vec serialization change. One-time cost, no user action needed in most cases.
• Users with existing cached repo: local Python hooks using . in additional_dependencies should run prek clean to pick up the new synthetic repo behavior.
• This fix is Python-specific for the synthetic local repo. Other languages with repo: local are not affected.

[codecov]

Codecov Report

❌ Patch coverage is 92.19858% with 11 lines in your changes missing coverage. Please review.
✅ Project coverage is 91.66%. Comparing base (4406340) to head (a9687f7).
⚠️ Report is 2 commits behind head on master.

Files with missing lines	Patch %	Lines
crates/prek/src/languages/python/python.rs	66.66%	6 Missing ⚠️
crates/prek/src/hook.rs	95.23%	4 Missing ⚠️
crates/prek/src/store.rs	88.88%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1609      +/-   ##
==========================================
- Coverage   91.68%   91.66%   -0.02%     
==========================================
  Files          94       94              
  Lines       18387    18516     +129     
==========================================
+ Hits        16858    16973     +115     
- Misses       1529     1543      +14     

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[prek-ci-bot]

📦 Cargo Bloat Comparison

Binary size change: +0.00% (23.7 MiB → 23.7 MiB)

Expand for cargo-bloat output

Head Branch Results

 File  .text    Size             Crate Name
 0.3%   0.8% 80.0KiB             prek? <prek::cli::Command as clap_builder::derive::Subcommand>::augment_subcommands
 0.3%   0.7% 71.2KiB              prek prek::languages::<impl prek::config::Language>::run::{{closure}}::{{closure}}
 0.3%   0.6% 65.6KiB              prek prek::languages::<impl prek::config::Language>::run::{{closure}}::{{closure}}
 0.2%   0.5% 54.4KiB              prek prek::languages::<impl prek::config::Language>::install::{{closure}}
 0.2%   0.5% 51.2KiB annotate_snippets annotate_snippets::renderer::render::render
 0.2%   0.4% 43.4KiB              prek prek::identify::by_extension::{{closure}}
 0.2%   0.4% 41.1KiB              prek prek::cli::run::run::run::{{closure}}
 0.2%   0.4% 38.8KiB              prek prek::run::{{closure}}
 0.1%   0.3% 32.0KiB             prek? <prek::cli::RunArgs as clap_builder::derive::Args>::augment_args
 0.1%   0.3% 28.4KiB      serde_saphyr saphyr_parser_bw::scanner::Scanner<T>::fetch_more_tokens
 0.1%   0.2% 24.8KiB             prek? <prek::config::_::<impl serde_core::de::Deserialize for prek::config::Config>::deserialize::__Visitor as serde_core::de::Visitor>::visit_map
 0.1%   0.2% 22.6KiB      serde_saphyr saphyr_parser_bw::scanner::Scanner<T>::fetch_more_tokens
 0.1%   0.2% 22.2KiB              prek prek::hooks::meta_hooks::MetaHooks::run::{{closure}}
 0.1%   0.2% 21.1KiB      clap_builder clap_builder::parser::parser::Parser::get_matches_with
 0.1%   0.2% 20.4KiB              prek prek::hooks::meta_hooks::MetaHooks::run::{{closure}}
 0.1%   0.2% 20.2KiB              prek <prek::languages::ruby::ruby::Ruby as prek::languages::LanguageImpl>::install::{{closure}}
 0.1%   0.2% 19.8KiB              prek prek::archive::unzip::{{closure}}
 0.1%   0.2% 19.7KiB               std core::ptr::drop_in_place<prek::languages::<impl prek::config::Language>::install::{{closure}}>
 0.1%   0.2% 19.5KiB              prek prek::cli::run::filter::collect_files_from_args::{{closure}}
 0.1%   0.2% 19.4KiB   cargo_metadata? <cargo_metadata::_::<impl serde_core::de::Deserialize for cargo_metadata::Package>::deserialize::__Visitor as serde_core::de::Visitor>::visit_map
38.3%  91.4%  9.1MiB                   And 20911 smaller methods. Use -n N to show more.
41.9% 100.0% 10.0MiB                   .text section size, the file size is 23.7MiB

Base Branch Results

 File  .text    Size             Crate Name
 0.3%   0.7% 70.6KiB             prek? <prek::cli::Command as clap_builder::derive::Subcommand>::augment_subcommands
 0.3%   0.7% 70.3KiB              prek prek::languages::<impl prek::config::Language>::run::{{closure}}::{{closure}}
 0.3%   0.6% 65.6KiB              prek prek::languages::<impl prek::config::Language>::run::{{closure}}::{{closure}}
 0.2%   0.5% 51.2KiB annotate_snippets annotate_snippets::renderer::render::render
 0.2%   0.5% 50.5KiB              prek prek::languages::<impl prek::config::Language>::install::{{closure}}
 0.2%   0.4% 43.4KiB              prek prek::identify::by_extension::{{closure}}
 0.2%   0.4% 41.8KiB              prek prek::cli::run::run::run::{{closure}}
 0.2%   0.4% 38.8KiB              prek prek::run::{{closure}}
 0.1%   0.3% 32.0KiB             prek? <prek::cli::RunArgs as clap_builder::derive::Args>::augment_args
 0.1%   0.3% 28.4KiB      serde_saphyr saphyr_parser_bw::scanner::Scanner<T>::fetch_more_tokens
 0.1%   0.2% 24.8KiB             prek? <prek::config::_::<impl serde_core::de::Deserialize for prek::config::Config>::deserialize::__Visitor as serde_core::de::Visitor>::visit_map
 0.1%   0.2% 22.6KiB      serde_saphyr saphyr_parser_bw::scanner::Scanner<T>::fetch_more_tokens
 0.1%   0.2% 22.2KiB              prek prek::hooks::meta_hooks::MetaHooks::run::{{closure}}
 0.1%   0.2% 22.2KiB              prek prek::hooks::meta_hooks::MetaHooks::run::{{closure}}
 0.1%   0.2% 21.1KiB      clap_builder clap_builder::parser::parser::Parser::get_matches_with
 0.1%   0.2% 20.0KiB   cargo_metadata? <cargo_metadata::_::<impl serde_core::de::Deserialize for cargo_metadata::Package>::deserialize::__Visitor as serde_core::de::Visitor>::visit_map
 0.1%   0.2% 19.8KiB              prek prek::archive::unzip::{{closure}}
 0.1%   0.2% 19.6KiB              prek prek::cli::run::filter::collect_files_from_args::{{closure}}
 0.1%   0.2% 19.3KiB               std core::ptr::drop_in_place<prek::languages::<impl prek::config::Language>::install::{{closure}}>
 0.1%   0.2% 19.2KiB              prek <prek::languages::ruby::ruby::Ruby as prek::languages::LanguageImpl>::install::{{closure}}
38.4%  91.5%  9.1MiB                   And 20946 smaller methods. Use -n N to show more.
42.0% 100.0% 10.0MiB                   .text section size, the file size is 23.7MiB