fix(agent): stop fabricated success confirmations (#363)

[AlanAAG]

Summary

CraftBot's agent was confirming actions it never performed: claiming it disabled an integration setting with no action call behind it, and claiming a Gmail "signature" was added when no signature capability exists anywhere in the codebase. Under user pushback, it escalated to inventing a new fabricated explanation on each retry instead of repeating the honest answer.

Root cause was three compounding gaps: no instruction to ground confirmation text in actual action evidence, an absolutist "never say you can't" prompt rule with no carve-out for genuine incapability, and stale/missing docs on what settings the agent can and can't actually change.

• agent_core/core/prompts/context.py, action.py — add a non-negotiable honesty rule to every action-selection prompt: once a capability is genuinely checked and confirmed absent, say so plainly ("there's no way I can do that") instead of faking success; pushback from the user does not change the honest answer, so don't invent a new excuse on retry.
• app/data/action/send_message.py — same reinforcement on the schema description, at the exact point the confirmation text gets composed.
• agent_file_system/AGENT.md (+ app/data/agent_file_system_template/AGENT.md) —
  • Documents set_requirement for the first time (it was in use but entirely undocumented): check feasibility before locking a requirement in; only mark satisfied when grounded in real action evidence; flip to violated immediately if the user disputes it rather than silently retrying.
  • Corrects a claim that per-integration settings are editable via the six main app/config/*.json files (they aren't — most integrations have their own .credentials/<name>_config.json, or no runtime config at all).
  • New guidance for editing those per-integration config files directly: read-merge-write-verify, since a blind overwrite can wipe other saved fields (6 integrations have multi-field configs).
• craftos_integrations/integrations/gmail/INTEGRATION.md, outlook/INTEGRATION.md — explicit "no signature feature exists, ever" note naming and banning the specific fabrications already observed in testing.
• tests/test_prompt_honesty_rules.py — presence-guard tests (6 cases) for both the always-injected framework-prompt layer and the integrations have their own .credentials/<name>_config.json, or no runtime config at all).
  • New guidance for editing those per-integration config files directly: read-merge-write-verify, since a blind overwrite can wipe other saved fields (6 integrations have multi-field configs).
• craftos_integrations/integrations/gmail/INTEGRATION.md, outlook/INTEGRATION.md — explicit "no signature feature exists, ever" note naming and banning the specific fabrications already observed in testing.
• tests/test_prompt_honesty_rules.py — presence-guard tests (6 cases) for both the always-injected framework-prompt layer and the read-on-demand doc layer, so neither can silently regress.

Deploy note: the framework prompt changes (action.py, context.py, send_message.py) are loaded once at process start — a running CraftBot instance needs to be restarted to pick them up. The AGENT.md/INTEGRATION.md doc changes take effect immediately with no restart.

Test plan

• python3 -m pytest tests/test_prompt_honesty_rules.py -v — 6/6 passing
• python3 -m pytest tests/ -q — 101 passed; 4 pre-existing failures in test_trigger_router_and_parking.py confirmed present on clean main before this change (unrelated FakeLLM/prompt_name kwarg mismatch)
• Live conversation test after restart: ask CraftBot to change a setting it can't (e.g. a nonexistent integration toggle) and confirm it says so instead of fabricating success
• Live conversation test after restart: ask for a Gmail signature on a sent email, push back once, confirm the agent repeats the same honest answer instead of inventing a new explanation

Closes #363

[AlanAAG]

Handles two specific error cases + general behaviour, if there are more specific issues where the agent wrongly confirms an action, please comment to be included in this pr