chore: remove unused httpx2 dev dependency

[Priyanshubhartistm]

Summary

• Remove the unused httpx2>=2.5.0 dev dependency from pyproject.toml and regenerate uv.lock.

Why

pyproject.toml's [dependency-groups].dev declared httpx2>=2.5.0, which looks like a typo for the httpx package. Nothing in src/ or tests/ imports httpx2 — the HTTP-exercising tests (tests/test_ingest_workflow.py, tests/test_web_source_runtime.py) import plain httpx, which is already a runtime dependency (httpx>=0.28.1). The stray dev dependency pulled its own httpx2, httpcore2, and truststore packages into every uv sync and CI run for nothing, and a near-name package that shadows a real dependency in the manifest is confusing for anyone auditing the dependency tree.

Related Issues #33

Verification

uv sync --locked
uv run ruff check .
uv run pytest
uv run codealmanac --help
uv build --out-dir dist
uvx twine check dist/*
git diff --check

All passed: uv sync --locked uninstalled httpx2/httpcore2/truststore; ruff check reported no issues; pytest passed 464/464; codealmanac --help printed the normal command list; uv build produced a valid wheel and sdist; twine check passed both artifacts; git diff --check found no whitespace issues.

Docs and wiki

• README/docs updated if user-facing behavior changed.
• .almanac/ wiki updated if an implementation decision, workflow, invariant, or gotcha changed.
• Not applicable.

Notes for reviewers

Dependency-only change, no source or test code touched. git grep -n httpx2 src tests confirms zero usages before and after. The uv.lock diff looks large in line count, but git diff uv.lock | grep '^[+-]name = ' shows only three package entries removed (httpx2, httpcore2, truststore) — the rest is the lockfile re-serializing after the dependency graph shrank.