feat: add resource caching and progress spinner for init/pull/branch

[amansingh1720]

Summary

Batch MultiResourceYamlResource writes during poly init so each YAML file is written once instead of once per resource, and add a progress spinner to init, pull, and branch switch so the CLI doesn't appear stuck on large projects.

Also edited CONTRIBUTING.md to edit the clone url - changed org to PolyAI.

Motivation

poly init is very slow on projects with many pronunciations (or other multi-resource YAML types) because save() rewrites the full YAML file for every single item. On large projects like pacden, the process appears stuck with no output. The save_to_cache + write_cache_to_file pattern already exists for poly pull — this reuses it for init and adds a progress spinner across all three commands.

Changes

• Use save_to_cache=True for all MultiResourceYamlResource saves during init_project(), then flush to disk once via write_cache_to_file()

• Add an optional on_save(current, total) callback to init_project(), pull_project(), _update_multi_resource_yaml_resources(), _update_pulled_resources(), and switch_branch() for progress reporting

• Wire up console.status() spinners in cli.py for init, pull, and branch switch, using nullcontext to skip the spinner in --json mode

• Progress counter includes both multi-resource (per batch total) and non-multi-resource types for an accurate total

• CONTRIBUTING.md to edit the clone url - changed org from PolyAI-LDN to PolyAI.

Test strategy

• Added/updated unit tests
• Manual CLI testing (poly <command>)
• Tested against a live Agent Studio project
• N/A (docs, config, or trivial change)

Checklist

• ruff check . and ruff format --check . pass
• pytest passes (361 tests, 0 failures)
• No breaking changes to the poly CLI interface (or migration path documented)
• Commit messages follow conventional commits

Screenshots / Logs

Before:

After:

[amansingh1720]

adding tests with on_save and current/total

[github-actions]

Coverage Report

Base (main)	PR	Change
70.2%	70.6%	+0.4% ✅

Changed file coverage

File	Coverage	Change
poly/cli.py	30.6%	-0.7% ⚠️
poly/project.py	66.1%	+2.2% ✅
poly/resources/pronunciation.py	71.9%	+2.1% ✅
poly/resources/resource.py	79.5%	+1.7% ✅
poly/resources/keyphrase_boosting.py	91.8%	+1.6% ✅

[Ruari-Phipps]

We shouldn't pass on save if doing --json output

[amansingh1720]

that is already handled with this - on_save=None is passed to the function and inside project.py, the callback is guarded by if on:save so its effectively a no-op.
when output_json is True then
ctx = nullcontext() (no-op) from this line
console.status("[info]Saving resources...[/info]") if not output_json else nullcontext()
on_save = None
status is None inside the with block
'if status: False', so on_save stays None and falls outside the if block

• This was done to try and avoid duplication

[amansingh1720]

poly/cli.py | 30.6% | -0.7% ⚠️
Can't really add test coverage for this since it would require a running terminal :/

[Ruari-Phipps]

LGTM!