Upstream integration cycle: web interaction fixes, ACP diagnostics, and Claude continuation

[rynfar]

Closes recent upstream bug fixes and UI alignments from upstream head 7445aa733ada33e45289e5aa5055f79142556513. Pylon head at open ee01ed60b09333939e48f362afa4601ce8285a13. Review cursor stays at bbedad0278bbf753503184c00e0c09a0eab6679c.

Group A — Web interaction & UI fixes (5 sources)

SHA	Upstream	Description
e36725682bd2935f1bcfdf81660cb569b5f3df29	#12577	fix(web): keep typed text when a question option is clicked
8dd02470b1e7603b8d36a21ae27c510480351f18	#12552	fix(web): restore providers settings heading
dcf8942304cfef382af55c0068cb2f04c86757fc	#12636	fix(web): keep desktop annotation screenshots under CSP
7445aa733ada33e45289e5aa5055f79142556513	#11263	fix(web): align menu item icons in pull request detail panel
599c9776eb887d4fff42da7d2daf8aa07ee9a9e2	#11268	fix(web): align pull request state glyph to top of row

Group B — Server & Desktop runtime fixes (3 sources)

SHA	Upstream	Description
63ff33756c47f127391962458d8388a647e8ed44	#12624	fix(server): empty Claude homePath shares continuation with ~/.claude
d6f291303ddc0c9a14f570266a4d9eff6d431593	#12625	fix(server): surface ACP stderr when cursor-agent exits at session start
52d08a14b9e475371658fabbb12c056c3d3dad67	#12635	fix(desktop): include SnapShot app text for Flatpak and GTK4

Boundaries to preserve

• Pylon's prompt/draft store and composer interaction state.
• Desktop CSP rules and image compression helpers.
• Provider driver lifecycle and Effect service architecture in @t3tools/server.
• Pylon PR panel layout, keybindings, and routing.

Review method

Adversarial review on every group by an independent reviewer that did not write the code. All findings must be addressed prior to landing.

Verification plan

• Scoped unit tests for web, server, and desktop.
• Typechecks across @t3tools/web, @t3tools/server, @t3tools/desktop, and @t3tools/effect-acp.
• Scoped lint and format passes.
• All CI jobs green on final PR heads.