fix(ask): enforce read-only contract; fix compact.md heading spacing

Remove Shell from ask.yaml allowed_tools — the mode is declared read-only
and Shell allows arbitrary mutating commands, breaking the contract.

Add blank lines around all headings in compact.md to satisfy MD022.

Author: elkaix

src/pythinker_code/agents/default/ask.yaml

@@ -26,7 +26,6 @@ agent:
     - "pythinker_code.tools.agent:RunAgents"
     - "pythinker_code.tools.skill:ReadSkill"
     - "pythinker_code.tools.ask_user:AskUserQuestion"
-    - "pythinker_code.tools.shell:Shell"
     - "pythinker_code.tools.file:ReadFile"
     - "pythinker_code.tools.file:ReadMediaFile"
     - "pythinker_code.tools.file:Glob"

src/pythinker_code/prompts/compact.md

@@ -6,31 +6,41 @@ The above is a list of messages in an agent conversation. Compact it into a stab
 Output exactly the Markdown structure shown below. Keep section names and order unchanged. Use terse bullets, not prose paragraphs. Preserve exact file paths, commands, error strings, identifiers, user constraints, and verification results when known. Do not mention the summary process or that context was compacted.
 
 ## Goal
+
 - [single-sentence summary of the user's current objective]
 
 ## Constraints & Preferences
+
 - [user constraints, project rules, style preferences, approvals/trust boundaries, or "(none)"]
 
 ## Progress
+
 ### Done
+
 - [completed work and verified outcomes, or "(none)"]
 
 ### In Progress
+
 - [current partial work, active branch/session state, or "(none)"]
 
 ### Blocked
+
 - [blockers, missing info, unavailable tools, or "(none)"]
 
 ## Key Decisions
+
 - [decision and why it was chosen, or "(none)"]
 
 ## Next Steps
+
 - [ordered next actions with acceptance/verification where known, or "(none)"]
 
 ## Critical Context
+
 - [important technical facts, errors and resolutions, risks, assumptions, or "(none)"]
 
 ## Relevant Files
+
 - [path: why it matters and latest known state, or "(none)"]
 
 Rules: