ParsedRelease.tech_string was a stored str field re-computed in two
places (assemble() at parse time, enrich_from_probe() after the probe).
The second site was a reactive fix (e79ca46) for filename builders that
saw a stale value. Turn it into an @property so it stays in sync with
quality/source/codec by construction.
- Drop the field from the dataclass + the key from assemble()'s dict.
- Drop tech_string="" from parse_release's malformed-name fallback.
- Drop the manual recomputation at the end of enrich_from_probe.
- Inject the property into asdict() result in the fixtures runner
(same treatment as is_season_pack).
- Update tests that passed tech_string= to the constructor; rewrite the
TestTechString case that mutated p.tech_string manually.
francwa
e62dc90bd1