Add visible episode selection to season workspaces

[cbusillo]

Summary

• add a complete, ordered Choose an episode control to TV season workspaces before sample/size actions
• show each episode's plain-language workflow state without starting work on selection
• route exact-item workspaces back to their parent season instead of only back to the library
• preserve complete pagination-backed episode access for large seasons and responsive narrow layouts

Validation

• bash scripts/pre-commit-check.sh
• full commit hook acceptance gate
• real-browser Stranger Things Season 1 review at 1024×768 and 390×844
• verified all eight episodes appear in numeric order
• verified selecting Episode 2 opens its exact workspace and starts no sample or encode
• verified the exact-item header links back to Season 1
• PyCharm changed-file inspection attempted through the required helper and its internal retry; the IDE returned stale results with no actionable finding

Closes #528
Unblocks #494 after merge.