feat(telemetry): track upgrade suggestion shown on 402 errors

[pamelachia]

Summary

Adds a cli_upgrade_suggested PostHog event that fires whenever the CLI displays a billing upgrade link after receiving a 402 Payment Required response. This lets us measure how often users hit plan-gated features from the CLI and size the upgrade conversion opportunity.

Changes

• Add EventUpgradeSuggested (cli_upgrade_suggested) event constant with feature_key and org_slug properties to telemetry catalog
• Change SuggestUpgradeOnError to return (string, bool) providing the resolved org slug and whether a 402 was detected
• Wire telemetry capture into branches create and branches update error paths, passing both feature_key and org_slug

Testing

Tested locally:

• All TestSuggestUpgradeOnError subtests pass, including (string, bool) return assertions
• All internal/branches/... tests pass (create, update, delete, list, etc.)
• All internal/telemetry/... tests pass
• No import cycle (telemetry event fired from callers, not from utils package)

Linear

• fixes GROWTH-757

[coveralls]

Coverage Report for CI Build 24125911620

Coverage decreased (-0.05%) to 63.79%

Details

• Coverage decreased (-0.05%) from the base build.
• Patch coverage: 10 uncovered changes across 2 files (16 of 26 lines covered, 61.54%).
• 5 coverage regressions across 1 file.

Uncovered Changes

File	Changed	Covered	%
internal/branches/create/create.go	10	5	50.0%
internal/branches/update/update.go	10	5	50.0%

Coverage Regressions

5 previously-covered lines in 1 file lost coverage.

File	Lines Losing Coverage	Coverage
internal/utils/git.go	5	57.14%

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Coverage Stats

Relevant Lines:	15330
Covered Lines:	9779
Line Coverage:	63.79%
Coverage Strength:	6.89 hits per line

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💛 - Coveralls