v3: SourceShell.fetch set_type() makes Collection identity locale-dependent

[markvp]

Found while reviewing the release/3.0.0 branch. Severity: medium.

Collection._identity_key (collection.py:178-198) is deliberately built on WasteType.id, not the display name, to keep equality and hashing locale-independent. But SourceShell.fetch calls set_type(e.type.strip()) on every entry (source_shell.py:208), so _type_override holds the localised display string and _identity_key then returns it. Any set or dedup keyed on Collection identity becomes locale-sensitive. Low blast radius today (the hot-path dedup uses (date, e.type) directly), but it defeats the design.

[markvp]

Fixed by #7020 (merged to release/3.0.0): SourceShell.fetch no longer sets _type_override on pipeline entries, so Collection identity stays locale-independent.