v0.7.5 — generic runtime context blocks

Highlights

• Generic context blocks — cllama now loads context-blocks.json and injects enabled every_turn blocks as runtime context with a kind tag.
• Placement control — blocks can render before feeds or after feeds, with after_feeds as the default late-salience placement before the time context.
• Operator visibility — context snapshots and telemetry now expose generic context_blocks / context_block_* fields instead of the earlier reminder-specific schema.