chore: improve automatic labeler

[seqre]

Description

Improve automatic labeling and align it with new labels.

Type of change

• Bug fix
• New feature
• Documentation
• Refactor / cleanup
• Performance improvement
• Other (describe above)

[Copilot]

Pull request overview

Updates GitHub automation configs to improve PR auto-labeling and to apply the new A-deps label to Dependabot-generated PRs.

Changes:

• Reworked .github/labeler.yml label definitions into “areas” and “crates”, adding new labels (A-ci, A-docs, A-deps) and updating file globs.
• Updated .github/dependabot.yml to add default assignees and apply the A-deps label to Dependabot PRs.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
.github/labeler.yml	Adds/renames label rules and updates glob patterns for auto-labeling.
.github/dependabot.yml	Adds assignees and A-deps label to Dependabot update PRs.

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[Copilot]

Same issue here: assignees expects individual GitHub usernames; an org/team slug like cot-rs/maintainers may break or be ignored by Dependabot. Prefer reviewers for a team, or list usernames under assignees.

[seqre]

@copilot provide docs pages that show reviewers is a valid field

[github-actions]

Bencher Report

Branch	automatic-labeler
Testbed	github-ubuntu-latest

Click to view all benchmark results

Benchmark	Latency	Benchmark Result microseconds (µs) (Result Δ%)	Upper Boundary microseconds (µs) (Limit %)
empty_router/empty_router	📈 view plot 🚷 view threshold	6,021.70 µs (+0.73%) Baseline: 5,977.82 µs	7,170.38 µs (83.98%)
json_api/json_api	📈 view plot 🚷 view threshold	1,026.50 µs (-0.64%) Baseline: 1,033.12 µs	1,191.23 µs (86.17%)
nested_routers/nested_routers	📈 view plot 🚷 view threshold	957.51 µs (+0.54%) Baseline: 952.34 µs	1,092.51 µs (87.64%)
single_root_route/single_root_route	📈 view plot 🚷 view threshold	927.26 µs (+1.50%) Baseline: 913.60 µs	1,051.21 µs (88.21%)
single_root_route_burst/single_root_route_burst	📈 view plot 🚷 view threshold	19,318.00 µs (+9.69%) Baseline: 17,610.86 µs	21,143.00 µs (91.37%)

🐰 View full continuous benchmarking report in Bencher

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

Flag	Coverage Δ
rust	89.99% <ø> (ø)

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