Fix base64 encoding for ocm-container CLI compatibility

[clcollins]

Summary

• Switch ALERT_DETAILS encoding from base64.RawURLEncoding to base64.RawStdEncoding
• RawURLEncoding uses URL-safe alphabet (-_) incompatible with base64 -d in ocm-container
• RawStdEncoding uses standard alphabet (+/) that base64 -d understands, while still omitting = padding that breaks ocm-container's env var parsing
• Fix pre-existing lint issues uncovered by CI: suppress errcheck on deferred asyncWriter.Close(), remove unused renderActionLogHeader() function, and remove empty test branch

Test plan

• Verify echo $ALERT_DETAILS | base64 -d | jq . works inside ocm-container after login
• Verify no = padding characters appear in the encoded value
• Run existing unit tests (go test ./pkg/tui/...)

🤖 Generated with Claude Code

[Copilot]

Pull request overview

This PR updates how the TUI passes PagerDuty alert details into ocm-container by changing the base64 encoding variant to improve CLI decode compatibility, and aligns related tests/docs cleanup.

Changes:

• Switch ALERT_DETAILS encoding from base64.RawURLEncoding to base64.RawStdEncoding (still unpadded).
• Update unit test expectations to match the new encoding/decoding behavior.
• Remove an unused view helper and adjust a couple of lint-related comments.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
README.md	Updates the ALERT_DETAILS encoding note (but leaves some surrounding wording inconsistent).
pkg/tui/commands.go	Changes ALERT_DETAILS encoding to RawStdEncoding for better base64 -d compatibility.
pkg/tui/commands_test.go	Updates base64 encoding/decoding in tests to RawStdEncoding.
pkg/tui/views.go	Removes unused renderActionLogHeader() helper.
pkg/tui/model_test.go	Replaces a comment block with an empty if plus nolint.
main.go	Adds //nolint:errcheck to deferred asyncWriter.Close().

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[Copilot]

Pull request overview

Copilot reviewed 6 out of 6 changed files in this pull request and generated 1 comment.

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[clcollins]

@clcollins PR #139 has been fully qualified.

Qualification Summary:

• Loops: 2 iteration(s) of Phases 1–4
• New commits: 2 commit(s) added during qualification
• Merge: No conflicts
• CI: All 2 checks passing (Lint Code, Run Unit Tests)
• Copilot: 3 comments addressed across 2 review rounds
• CodeRabbit: N/A (not enabled)
• Codecov: N/A (not enabled)

Intent validation: The PR still fulfills its original intent — switching ALERT_DETAILS encoding from RawURLEncoding to RawStdEncoding for base64 -d CLI compatibility. All changes made during qualification (lint fixes, README consistency, empty test branch removal) are consistent with the PR's purpose.

This PR is ready to merge.

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Qualified by Claude on behalf of @clcollins